Increased stiffness center optic in soft contact lenses for astigmatism correction

ABSTRACT

A molded contact lens comprising a stiffer optic zone relative to the peripheral zone of the contact lens provides an optical element for correcting astigmatism without the need for or substantially minimizing the need for the correction of rotational misalignment. The higher elastic modulus optic zone vaults over the cornea thereby allowing a tear lens to form. The tear lens follows or assumes the shape of the back surface of the contact lens. The combination of the tear lens and the optical zone provide an optical element for correction of refractive error.

FIELD OF THE INVENTION

The present invention relates to contact lenses having a higherstiffness in the central optic zone relative to the peripheral zone, andmore particularly to soft contact lenses incorporating a higher modulushydrogel material in the central optic zone relative to the peripheralzone for the correction of astigmatic refractive errors as well aspossible higher order aberrations created by corneal geometry. Thehigher modulus hydrogel material creates a stiffer central optic zonerelative to the peripheral zone of the contact lenses.

BACKGROUND

Myopia or nearsightedness is an optical or refractive defect of the eyewherein rays of light from an image focus to a point before they reachthe retina. Myopia generally occurs because the eyeball or globe is toolong or the shape or contour of the cornea is too steep. A minus poweredspherical lens may be utilized to correct myopia. Hyperopia orfarsightedness is an optical or refractive defect of the eye whereinrays of light from an image focus to a point after they reach or behindthe retina. Hyperopia generally occurs because the eyeball or globe istoo short or the shape or contour of the cornea is too flat. A pluspowered spherical lens may be utilized to correct hyperopia. Astigmatismis an optical or refractive defect in which an individual's vision isblurred due to the inability of the eye to focus a point object into afocused image on the retina. Unlike myopia and/or hyperopia, astigmatismis unrelated to globe size or corneal steepness, but rather it is causedby a non-rotationally symmetric cornea or from the misalignment orpositioning of the crystalline lens. The vast majority of astigmatismoccurs due to non-rotationally symmetric corneal curvature. A perfectcornea is rotationally symmetric whereas in most individuals withastigmatism, the cornea is not rotationally symmetric. In other words,the cornea is actually more curved or steeper in one direction thananother, thereby causing an image to be stretched out rather thanfocused to a point. A cylindrical lens or toric contact lens, ratherthan a spherical lens may be utilized to resolve astigmatism.

Corneal astigmatism may be corrected using a hard or rigid gas permeablecontact lens. In this case, a fluid or tear lens may exist between theposterior surface of the rigid contact lens and the cornea. This fluidor tear lens follows or assumes the shape of the back surface of thecontact lens. Since the index of refraction of the fluid or tear lens isnearly a match for the cornea, the corneal toricity is opticallyneutralized or reduced. In these cases, a toric lens will not berequired. However, rigid gas permeable contact lenses and hard contactlenses are generally less comfortable than soft or hydrogel contactlenses. Since soft or hydrogel contact lenses wrap around the cornea, afluid lens is generally not found and the tear fluid more closelyresembles a thin film. In this case, a toric lens design is required.

A toric lens is an optical element having two different powers in twoorientations that are perpendicular to one another. Essentially, a toriclens has one power, spherical, for correcting myopia or hyperopia andone power, cylinder, for correcting astigmatism built into a singlelens. These powers are created with curvatures at different angles whichare preferably maintained relative to the eye. Toric lenses may beutilized in eyeglasses, intraocular lenses and contact lenses. The toriclenses used in eyeglasses and intraocular lenses are held fixed relativeto the eye thereby always providing optimal vision correction. However,toric contact lenses may tend to rotate on the eye thereby temporarilyproviding sub-optimal vision correction. Accordingly, currently utilizedtoric contact lenses also include a mechanism to keep the contact lensrelatively stable on the eye when the wearer blinks or looks around. Formany high order aberrations, many of which are not rotationallysymmetric, positional stability is also required to provide optimalvision correction.

When a toric contact lens is first placed in the eye, it mustautomatically position or auto-position itself and it then maintainsthat position over time. However, once the toric contact lens ispositioned, it tends to rotate on the eye due to the force exerted onthe contact lens by the eyelids during blinking as well as eyelid andtear fluid movement. Maintenance of the on-eye orientation of a toriccontact lens is generally accomplished by altering the mechanicalcharacteristics of the toric contact lens. For example, prismstabilization, including decentering of the contact lens' front surfacerelative to the back surface, thickening of the inferior contact lensperiphery, forming depressions or elevations on the contact lens'surface, and truncating the contact lens edge are all methods that havebeen utilized.

Each of more traditional stabilization techniques have advantages anddisadvantages associated therewith. The main disadvantage of these typesof designs is that they rely on the interaction of the eyelids and thecontact lens' thickness differential to orient the contact lens to thecorrect location on the wearer's eye. The problem is particularly acutewith plus powered toric contact lenses intended for hyperopia.

Astigmatic masking lenses in which the lens vaults over the corneathereby creating a space between the corneal surface and the lens havealso been disclosed. Tear film fills that space and masks the astigmaticproperties of the cornea. Current masking lenses which have sufficientstiffness in the central region are either undesirably thick, or areincompatible with the hydrogel materials used in the periphery.

U.S. Pat. No. 4,166,255 discloses a hybrid contact lens based fromconventional hydrogels with a rigid central optical area surrounded byor embedded in a relatively soft transparent plastic component with aflexible periphery.

U.S. Pat. No. 4,701,288 disclosed a method of making a hybrid contactlens by sequential ultraviolet photopolymerizations with differentreactive mixtures in a mold to make a composite article from which acontact lens may be machined.

U.S. Pat. No. 5,923,397 disclosed a bimodulus contact lens comprising arigid gas permeable polymeric core and a softer end section attachedannularly around the core section.

U.S. Pat. No. 6,579,918 disclosed a method of making a composite contactlens in which one optical component is cast molded around a secondoptical component, thereby encapsulating the second optical component.

U.S. Pat. No. 8,662,663 disclosed a hybrid soft contact lens including acentral portion with a Young's modulus between 435 psi and 14,503 psiand a peripheral portion with a Young's modulus between 29 psi and 435psi.

However, current masking lenses which have sufficient stiffness in thecentral region are either undesirably thick, or are incompatible withthe hydrogel materials used in the periphery.

Accordingly, it would be advantageous to design contact lenses,including toric contact lenses, that correct for astigmatism as well aspossible higher order aberrations caused by corneal geometry with lessreliance on specific on-eye orientation and therefore less or nostabilization means.

SUMMARY OF THE INVENTION

In order for a soft contact lens to vault over the cornea surface, thecentral portion of the lens must be stiff enough to maintain the shaperequired for vaulting without causing patient discomfort at the sametime. The present invention is directed to silicone hydrogels that havesufficient stiffness for vaulting at relatively high water contents toform composite soft contact lenses with other silicone hydrogels thatare comfortable to wear.

In one embodiment of the present invention, composite contact lenses areprovided having a central region and a peripheral region, wherein thecentral region is formed from a silicone hydrogels formed from reactivemixtures comprising at least one N-alkyl methacrylamide, at least onesilicone-containing component, and at least one cross-linking agent, andoptional components including at least one hydrophilic monomer, at leastone wetting agent. These silicone hydrogels have water contents fromabout 10 weight percent to about 40 weight percent and moduli from about15,000 psi to about 75,000 psi. Silicone hydrogel formulations havingwater contents of about 10 to about 40 weight percent and moduli fromabout 20 to about 500 psi about 50 to about 200 psi, or about 50 toabout 150 psi monomers may be used in the peripheral region. Either thefirst, second or both silicone hydrogels may further comprise at leastone internal wetting agent and one or more hydrophilic component.

In another embodiment, a process for making such composite contactlenses is described comprising (a) dosing a first silicone hydrogelformulation of claim 1 into a first mold, (b) partially curing the firstsilicone hydrogel formulation into a gel, (c) dosing a second siliconehydrogel formulation into the first mold, (d) allowing time for thesecond silicone hydrogel formulation to imbibe into the gel, (e) placinga second mold on top of the first mold, and (f) fully curing thecombination to form the composite contact lens.

The present invention is also directed to a contact lens. The contactlens comprising an optic zone being formed from a material having awater content from about 10 weight percent to about 40 weight percentand Young's modulus between about 10,000 psi to about 200,000 psi, and aperipheral zone being formed from a material a having water content ofabout 10 to about 40 weight percent and Young's modulus from about 20 toabout 500 psi, less than 200 psi or less than 150 psi.

A method of making an ophthalmic device, the method comprising

dosing a first reactive mixture comprising at least one N-alkylmethacrylamide and at least one silicone-containing component, into acenter portion of a contact lens front curve mold;

dosing into the contact lens front curve mold on top of the firstmaterial, a second material having a second Young's modulus when curedof less than about 200 psi, and wherein the first material, when cured,has a first Young's modulus greater than about 1000, and wherein saidfirst and second reactive mixtures are substantially immiscible during aperiod from dosing to curing;

positioning a contact lens back curve mold on the second material; andcuring said reactive mixtures.

The present invention is also directed to a contact lens comprising anoptic zone being formed from a first material having a first Young'smodulus between about 1,000 psi and about 200,000 psi, said firstmaterial formed from a reactive mixture comprising at least one N-alkylmethacrylamide and at least one silicone-containing component; and aperipheral zone formed from a material having a second Young's modulusless than about 200 psi or about 150 psi.

The present invention is also directed to a contact lens comprising anoptic zone having a first stiffness, said optic zone being formed from afirst material having a first Young's modulus between about 1,000 psiand about 200,000 psi, said first material formed from a reactivemixture comprising at least one N-alkyl methacrylamide and at least onesilicone-containing component; and a peripheral zone having a secondstiffness formed from a material having a second Young's modulus lessthan about 200 psi or about 150 psi, the first stiffness being greaterthan the second stiffness.

Throughout the specification, the term stiffness should be understood tobe a function of the Young's modulus of the material, the thickness ofthe material, the shape of the material, and any tension or stress builtinto the material. Accordingly, for a given shape and a given thickness,a material with a higher Young's modulus will be stiffer than one with alower Young's modulus.

The present invention is directed to a contact lens having an increasedstiffness in the optic zone. This increased stiffness optic zone may beachieved in a number of ways, including utilizing a reactive mixture,which when cured provides a higher Young's modulus than the bulkmaterial forming the contact lens in the optic zone, utilizing asuitable additive for raising the Young's modulus in the optic zone, bymanufacturing the contact lens with specific processes such as varyingcure light intensity across the lens thereby causing an increase in thestiffness of the center of the lens, or by pre-tensioning of the contactlens to create resistance to deformation when placed on-eye. By having astiffer optical zone, the optic zone vaults over or does not conform tothe astigmatic geometry of the cornea while the remaining portion of thecontact lens does. This vaulting or lack of conformation allows a tearor fluid lens to form between the cornea and the optic zone. This tearor fluid lens follows or assumes the shape of the back surface of thecontact lens, which is rotationally symmetric or contains cylindercorrection smaller than the corneal astigmatism. Since tears havesubstantially the same index of refraction as that of the cornea, thefluid lens and the contact lens combination forms an optic surface orelement that corrects all or a portion of the visual deficit orrefractive error caused by the corneal geometry. In other words, sincethe index of refraction of the fluid or tear lens is nearly a match forthe cornea, the corneal toricity is optically neutralized or reducedwhen combined with the contact lens optics.

The contact lens of the present invention may be manufactured utilizingany suitable process without a significant increase in expense orcomplexity. This design may be implemented in any number or type of softcontact lenses.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages of the invention will beapparent from the following, more particular description of preferredembodiments of the invention, as illustrated in the accompanyingdrawings.

FIGS. 1a and 1b are a diagrammatic representation of the steps tomanufacture a contact lens in accordance with the present invention.

FIG. 2 is a planar view of a contact lens in accordance with the presentinvention.

DETAILED DESCRIPTION

With respect to the terms used in this disclosure, the followingdefinitions are provided. The polymer definitions are consistent withthose disclosed in the Compendium of Polymer Terminology andNomenclature, IUPAC Recommendations 2008, edited by: Richard G. Jones,Jaroslav Kahovec, Robert Stepto, Edward S. Wilks, Michael Hess, TatsukiKitayama, and W. Val Metanomski.

As used herein, the term “about” refers to a range of +/−5% of thenumber that is being modified. For example, the phrase “about 10” wouldinclude both 9.5 and 10.5.

The term “(meth)” designates optional methyl substitution. Thus, a termsuch as “(meth)acrylate” denotes both methacrylate and acrylateradicals. Wherever chemical structures are given, it should beappreciated that alternatives disclosed for the substituents on thestructure may be combined in any combination. Thus, if a structurecontained substituents R* and R**, each of which contained three listsof potential groups, 9 combinations are disclosed. The same applies forcombinations of properties.

When a subscript, such as “n” in the generic formula [***]_(n), is usedto depict the number of repeating units in a polymer's chemical formula,the formula should be interpreted to represent the number averagemolecular weight of the macromolecule.

A “macromolecule” is an organic compound having a molecular weight ofgreater than 1500, and may be reactive or non-reactive.

A “polymer” is a macromolecule of repeating chemical units linkedtogether into a chain or network structure and is composed of repeatingunits derived from the monomers and macromers included in the reactivemixture.

A “homopolymer” is a polymer made from one monomer or macromer; a“copolymer” is a polymer made from two or more monomers, macromers or acombination thereof; a “terpolymer” is a polymer made from threemonomers, macromers or a combination thereof. A “block copolymer” iscomposed of compositionally different blocks or segments. Diblockcopolymers have two blocks. Triblock copolymers have three blocks. “Combor graft copolymers” are made from at least one macromer.

A “repeating unit” or “repeating chemical unit” is the smallestrepeating group of atoms in a polymer that result from thepolymerization of monomers and macromers.

A “biomedical device” is any article that is designed to be used whileeither in or on mammalian tissues or fluids, and preferably in or onhuman tissue or fluids. Examples of these devices include but are notlimited to wound dressings, sealants, tissue fillers, drug deliverysystems, coatings, adhesion prevention barriers, catheters, implants,stents, sutures and ophthalmic devices such as intraocular lenses andcontact lenses. The biomedical devices may be ophthalmic devices, suchas contact lenses, including contact lenses made from siliconehydrogels.

“Individual” includes humans and vertebrates.

“Ocular surface” includes the surface and glandular epithelia of thecornea, conjunctiva, lacrimal gland, accessory lacrimal glands,nasolacrimal duct and meibomian gland, and their apical and basalmatrices, puncta and adjacent or related structures, including eyelidslinked as a functional system by both continuity of epithelia, byinnervation, and the endocrine and immune systems.

“Ophthalmic device” refers to any device which resides in or on the eyeor any part of the eye, including the ocular surface. These devices canprovide optical correction, cosmetic enhancement, vision enhancement,therapeutic benefit (for example as bandages) or delivery of activecomponents such as pharmaceutical and nutriceutical components, or acombination of any of the foregoing. Examples of ophthalmic devicesinclude, but are not limited to, lenses and optical and ocular inserts,including, but not limited to punctal plugs and the like. “Lens”includes soft contact lenses, hard contact lenses, hybrid contactlenses, intraocular lenses, and overlay lenses. The ophthalmic devicemay comprise a contact lens.

“Contact lens” refers to a structure, an ophthalmic device that can beplaced on the cornea of an individual's eye. The contact lens mayprovide corrective, cosmetic, therapeutic benefit, including woundhealing, delivery of drugs or neutraceuticals, diagnostic evaluation ormonitoring, or UV blocking and visible light or glare reduction, or acombination thereof. A contact lens can be of any appropriate materialknown in the art, and can be a soft lens, a hard lens, or a hybrid lenscontaining at least two distinct portions with different properties,such as modulus, water content, light absorbing characteristics orcombinations thereof.

The biomedical devices, ophthalmic devices, and lenses of the presentinvention may be comprised of silicone hydrogels. These siliconehydrogels typically contain a silicone component and/or hydrophobic andhydrophilic monomers that are covalently bound to one another in thecured device.

“Silicone hydrogel contact lens” refers to a contact lens comprising atleast one silicone hydrogel material. Silicone hydrogel contact lensesgenerally have increased oxygen permeability compared to conventionalhydrogels. Silicone hydrogel contact lenses use both their water andpolymer content to transmit oxygen to the eye.

A “polymeric network” is cross-linked macromolecule that can swell butcannot dissolve in solvents, because the polymeric network isessentially one macromolecule. “Hydrogel” or “hydrogel material” refersto a polymeric network that contains water in an equilibrium state.Hydrogels generally contain at least about 10 wt. % water.

“Conventional hydrogels” refer to polymeric networks made from monomerswithout any siloxy, siloxane or carbosiloxane groups. Conventionalhydrogels are prepared from monomeric mixtures predominantly containinghydrophilic monomers, such as 2-hydroxyethyl methacrylate (“HEMA”),N-vinyl pyrrolidone (“NVP”), N, N-dimethylacrylamide (“DMA”), or vinylacetate. U.S. Pat. Nos. 4,436,887, 4,495,313, 4,889,664, 5,006,622,5,039459, 5,236,969, 5,270,418, 5,298,533, 5,824,719, 6,420,453,6,423,761, 6,767,979, 7,934,830, 8,138,290, and 8,389,597 disclose theformation of conventional hydrogels. Commercially available hydrogelformulations include, but are not limited to, etafilcon, polymacon,vifilcon, genfilcon, lenefilcon, hilafilcon, nesofilcon, and omafilcon,including all of their variants.

“Silicone hydrogel” refers to a hydrogel obtained by copolymerization ofat least one silicone-containing component with at least one hydrophiliccomponent. Hydrophilic components may also include non-reactivepolymers. Each of the silicone-containing components and the hydrophiliccomponents may be a monomer, macromer or combination thereof. Asilicone-containing component contains at least one siloxane orcarbosiloxane group. Examples of commercially available siliconehydrogels include balafilcon, acquafilcon, lotrafilcon, comfilcon,delefilcon, enfilcon, fanfilcon, formofilcon, galyfilcon, senofilcon,narafilcon, falcon II, asmofilcon A, samfilcon, riofilcon, stenficlon,somofilcon, as well as silicone hydrogels as prepared in U.S. Pat. Nos.4,659,782, 4,659,783, 5,244,981, 5,314,960, 5,331,067, 5,371,147,5,998,498, 6,087,415, 5,760,100, 5,776,999, 5,789,461, 5,849,811,5,965,631, 6,367,929, 6,822,016, 6,867,245, 6,943,203, 7,247,692,7,249,848, 7,553,880, 7,666,921, 7,786,185, 7,956,131, 8,022,158,8,273,802, 8,399,538, 8,470,906, 8,450,387, 8,487,058, 8,507,577,8,637,621, 8,703,891, 8,937,110, 8,937,111, 8,940,812, 9,056,878,9,057,821, 9,125,808, 9,140,825, 9,156,934, 9,170,349, 9,244,196,9,244,197, 9,260,544, 9,297,928, 9,297,929 as well as WO 03/22321, WO2008/061992, and US 2010/048847. These patents, as well as all otherpatents disclosed in this paragraph, are hereby incorporated byreference in their entireties

“Silicone-containing component” refers to a monomer, macromer,prepolymer, cross-linker, initiator, additive, or polymer that containsat least one silicon-oxygen bond, in the form of siloxane [—Si—O—Si]group or carbosiloxane group. Examples of silicone-containing componentsinclude, but are not limited to, silicone macromers, prepolymers, andmonomers. Examples of silicone macromers include, but are not limitedto, polydimethylsiloxane methacrylated with pendant hydrophilic groups.Examples of silicone-containing components which are useful in thisinvention may be found in U.S. Pat. Nos. 3,808,178, 4,120,570,4,136,250, 4,153,641, 4,740,533, 5,034,461, 5,962,548, 5,244,981,5,314,960, 5,331,067, 5,371,147, 5,760,100, 5,849,811, 5,962,548,5,965,631, 5,998,498, 6,367,929, 6,822,016, 5,070,215, U.S. Pat. Nos.8,662,663, 7,994,356, 8,772,422, 8,772,367, EP080539 and WO2014/123959.

“Reactive mixture” and “reactive monomer mixture” refer to the mixtureof components (both reactive and non-reactive) which are mixed togetherand when subjected to polymerization conditions, form the siliconehydrogels and lenses of the present invention. The reactive mixturecomprises reactive components such as monomers, macromers, prepolymers,cross-linkers, initiators, diluents, and additional components such aswetting agents, release agents, dyes, light absorbing compounds such asUV absorbers, pigments, dyes and photochromic compounds, any of whichmay be reactive or non-reactive but are capable of being retained withinthe resulting biomedical device, as well as active components such aspharmaceutical and neutraceutical compounds, and any diluents. It willbe appreciated that a wide range of additives may be added based uponthe biomedical device which is made, and its intended use.Concentrations of components of the reactive mixture are given in weight% of all components in the reaction mixture, excluding diluent. Whendiluents are used their concentrations are given as weight % based uponthe amount of all components in the reaction mixture and the diluent.

“Monomer” is a molecule having non-repeating functional groups, whichcan undergo chain growth polymerization, and in particular, free radicalpolymerization. Some monomers have di-functional impurities that can actas cross-linking agents. “Macromers” are linear or branched polymershaving a repeating structure and at least one reactive group that canundergo chain growth polymerization. Monomethacryloxypropyl terminatedmono-n-butyl terminated polydimethylsiloxane (molecular weight=500-1500g/mol) (mPDMS) and mono-(2-hydroxy-3-methacryloxypropyl)-propyl etherterminated mono-n-butyl terminated polydimethylsiloxane (molecularweight=500-1500 g/mol) (OH-mPDMS) are referred to as macromers.

“Reactive components” are the components in the reactive mixture whichbecome part of the structure of the polymeric network of the resultingsilicone hydrogel, by covalent bonding, hydrogen bonding or theformation of an interpenetrating network. Diluents and processing aidswhich do not become part of the structure of the polymer are notreactive components. Typically, the chemical structure of the macromeris different than the chemical structure of the target macromolecule,that is, the repeating unit of the macromer's pendent group is differentthan the repeating unit of the target macromolecule or its mainchain.

“Polymerizable” means that the compound comprises at least one reactivegroup which can undergo chain growth polymerization, such as freeradical polymerization. Examples of reactive groups include themonovalent reactive groups listed below. “Non-polymerizable” means thatthe compound does not comprises such a polymerizable group.

“Monovalent reactive groups” are groups that can undergo chain growthpolymerization, such as free radical and/or cationic polymerization.Non-limiting examples of free radical reactive groups include(meth)acrylates, styrenes, vinyl ethers, (meth)acrylamides,N-vinyllactams, N-vinylamides, O-vinylcarbamates, O-vinylcarbonates, andother vinyl groups. In one embodiment, the free radical reactive groupscomprise (meth)acrylate, (meth)acrylamide, N-vinyl lactam, N-vinylamide,and styryl functional groups, or (meth)acrylates, (meth)acrylamides, andmixtures of any of the foregoing.

Examples of the foregoing include substituted or unsubstitutedC₁₋₆alkyl(meth)acrylates, C₁₋₆alkyl(meth)acrylamides, C₂₋₁₂alkenyls,C₂₋₁₂alkenylphenyls, C₂₋₁₂alkenylnaphthyls, C₂₋₆alkenylphenylC₁₋₆alkyls,where suitable substituents on said C₁₋₆ alkyls include ethers,hydroxyls, carboxyls, halogens and combinations thereof.

Other polymerization routes such as living free radical and ionicpolymerization can also be employed. The device-forming monomers mayform hydrogel copolymers. For hydrogels, the reactive mixture willtypically include at least one hydrophilic monomer.

Hydrophilic components are those which yield a clear single phase whenmixed with deionized water at 25° C. at a concentration of 10 wt. %.

“Interpenetrating polymer networks” or “IPNs” are polymers comprisingtwo or more polymeric networks which are at least partially interlacedon a molecular scale, but not covalently bonded to each other and cannotbe separated unless chemical bonds are broken.

“Semi-interpenetrating polymer networks” or “semi-IPNs” are polymercomprising one or more polymer network(s) and one or more linear orbranched polymer(s) characterized by the penetration on a molecularscale of at least one of the networks by at least some of the linear orbranched chains. A “cross-linking agent” is a di-functional ormulti-functional component which can undergo free radical polymerizationat two or more locations on the molecule, thereby creating branch pointsand a polymeric network. Common examples are ethylene glycoldimethacrylate, tetraethylene glycol dimethacrylate, trimethylolpropanetrimethacrylate, methylene bisacrylamide, triallyl cyanurate, and thelike.

For purposes of the present invention a contact lens is defined by atleast two distinct regions. The inner region or optical zone from whichthe vision correction is obtained and the outer peripheral zone of thecontact lens that provides mechanical stability of the contact lens oneye. In some cases, an optional intermediate zone or region locatedbetween the inner optical zone and the outer peripheral zone may be usedfor blending the two aforementioned zones in a smooth manner such thatdiscontinuities do not occur. A contact lens is also defined by a frontsurface or surface power, a back curve or base curve and an edge.

The inner region or optical zone provides vision correction and isdesigned for a specific need such as single vision myopia or hyperopiacorrection, astigmatism vision correction, bi-focal vision correction,multi-focal vision correction, custom correction or any other designthat may provide vision correction. The outer periphery or peripheralzone provides mechanical features which influence positioning andstabilization of the contact lens on the eye including, centration andorientation. Orientation stabilization is fundamental when the opticalzone includes non-rotationally symmetric features, such as astigmaticcorrection and/or high order aberrations correction. The optionalintermediate region or zone ensures that the optical zone and theperipheral zone are smoothly blended. It is important to note that boththe optical zone and the peripheral zone may be designed independently,though sometimes their designs are strongly related when particularrequirements are necessary.

Referring now to FIG. 1, there is illustrated a planar view of anexemplary contact lens design or construct in accordance with thepresent invention. The contact lens 100 comprises an optic zone 102 anda peripheral zone 104 surrounding the optic zone 102. This arrangementor configuration is a standard contact lens design. In accordance withthe present invention; however, the optic zone 102 is modified, asdetailed subsequently, to be stiffer than the surrounding region;namely, the peripheral zone 104. The optic zone 102 may be made stifferthan the peripheral zone 104 via a number of methods and means as isdiscussed subsequently. The stiffer optic zone 102 may be achievedutilizing a material with a higher Young's modulus or higher elasticmodulus in the optic zone 102 than the material in the peripheral zone104. In addition to being of higher elastic modulus, the material in theoptic zone 102 may also have a higher viscosity, than the secondhydrogel reactive mixture, such that the first silicone hydrogelreactive mixture remains fixed in position. The first silicone hydrogelmixture may also be partially or fully cured prior to dosing the secondhydrogel reactive mixture.

It is desirable to minimize the generation of stresses at the interfacebetween the first and second hydrogel polymers in the resulting lens.This may be done by substantially matching the water content and/orexpansion of the first and second hydrogel reactive mixtures.

It has been found that by balancing the expansion factor of the polymersformed from the photochromic dye monomer mixture and the clear monomermixture hydrogel contact lenses having desirable optics and comfort maybe produced. In one embodiment the expansion factors of the polymersformed from the respective monomer mixtures are within about 10% in someembodiments within about 8% and in other embodiments within about 5%.The expansion factor may be adjusted by manipulating a number offormulation variables including the diluent concentration, theconcentration and hydrophilicity or hydrophobicity of hydrophilic andhydrophobic components and concentration of initiator and crosslinker,and combinations thereof. Many photochromic dyes are highly hydrophobicand at the concentrations used in the present invention can have animpact on the expansion factor the hydrogels which contain them. In oneembodiment, where the photochromic dye is hydrophobic, it is added tothe formulation replacing a similar amount of another hydrophobiccomponent. Similarly, if the photochromic compound were hydrophilic itwill be added to the formulation replacing a similar amount of anotherhydrophilic component. In some embodiments, for example, where asilicone hydrogel contact lens is being produced, it may be desirable tomaintain the concentration of the silicone components and replace a partof one of hydrophilic components. In these embodiments, multipleadjustments may be needed to achieve the desired expansion factor.

In addition, other formulation variables may be modified to achieve thedesired expansion factor. In some embodiments varying the concentrationof the hydrophilic components, the diluent concentration and theinitiator concentration, and combinations thereof have been effective atproviding photochromic contact lenses having desirable optics andcomfort. In one embodiment a hydrophilic polymer, such as poly(vinylpyrrolidone) (PVP), methacrylic acid, polydimethylacrylamide orpoly(vinyl methacetamide) may be added to the photochromic dye monomermixture.

It may be desirable to use the same or similar components in both thecentral and peripheral zones. For example, it may be desirable toinclude the same hydrophilic components in both reactive mixtures. Inthis case, formulation variables in addition to the concentration ofhydrophilic components may be varied.

When a single sided cure is used, the expansion factor may be matchedusing monomers, diluent concentration and combinations thereof. Wherecure is effected from only one side (such as during photocuring),increasing the initiator concentration may also be desirable.

The peripheral region may be formed from contact lens materials madefrom HEMA based hydrogel or silicone hydrogel materials, which includebut are not limited to silicone hydrogels, and fluorohydrogels. Examplesof soft contact lenses formulations include but are not limited to theformulations of etafilcon A, genfilcon A, lenefilcon A, polymacon,acquafilcon A, balafilcon A, galyfilcon A, senofilcon, narafilcon A,narafilcon B, comfilcon, filcon II 3, asmofilcon, Monomer A andlotrafilcon A, and the like. Silicone hydrogels formulations, such asthose disclosed in U.S. Pat. No. 5,998,498; U.S. patent application Ser.No. 09/532,943, a continuation-in-part of U.S. patent application Ser.No. 09/532,943, filed on Aug. 30, 2000, and U.S. Pat. No. 6,087,415,U.S. Pat. No. 6,087,415, U.S. Pat. No. 5,760,100, U.S. Pat. No.5,776,999, U.S. Pat. No. 5,789,461, U.S. Pat. No. 5,849,811, U.S. Pat.No. 5,965,631, U.S. Pat. No. 7,553,880, WO2008/061992, US2010/048847,may also be used. These patents are hereby incorporated by reference forthe hydrogel compositions contained therein. In one embodiment contactlens formulations are selected from etafilcon A, balafilcon A,acquafilcon A, lotrafilcon A, galyfilcon A, senfilcon, comfilcon,narafilcon, Monomer A and silicone hydrogels.

A material with a higher Young's modulus is stiffer than a material witha lower Young's modulus. The stiffness of a component, element and/orpart determines how much it will deflect under a given load. The morestiff a material is, the higher the load required to elastically deformit; however, the stiffness of an element is also a function of thematerial thickness as well as the shape of the element. Accordingly, fora given shape and thickness, the higher the Young's modulus, the greaterthe stiffness. With this type of design, astigmatic correction may beachieved via an increase in the contact lens stiffness for arotationally or non-rotationally symmetric optic zone, in order tooptically neutralize or reduce the effect of corneal astigmatism, byproviding for the central optic or optic zone 102 of the contact lens100 to vault over the astigmatic geometry of the cornea. In other words,the optic zone 102 vaults over, or does not conform to, the astigmaticgeometry of the cornea while the peripheral zone 104 remains in contactwith the eye such that a thicker tear fluid lens forms between thecornea and the optic zone 102. Since tears have substantially the sameindex of refraction as that of the cornea, the tear fluid lens and thecontact lens combination form an optic surface or element that correctsthe visual deficit or refractive error caused by the corneal geometry.In other words, given that the index of refraction of the fluid or tearlens is nearly a match for the cornea; the corneal toricity is opticallyneutralized or reduced when combined with the contact lens optics. Anadvantage of the present invention is that in reducing or eliminatingthe need for the contact lens to contain non-rotationally symmetricoptical correction, the stabilization features may be reduced in size oreliminated, thereby providing a more comfortable lens.

Based upon the specific stiffness achieved through the first siliconehydrogel material having a modulus of about 10,000 to about 200,000 psi,15,000 psi to about 100,000 psi in combination with the specific lensgeometry, for example, spherical, aspheric and/or toric, on top of anastigmatic corneal geometry, a contact lens designed in this manner maybe utilized for the correction of low levels of astigmatism and also maybe selectively utilized to enhance vision for higher amounts ofastigmatism as well as any possible higher order aberrations created bycorneal geometry. Accordingly, the present invention utilizes a contactlens with a specific prescription, but formed with an optic zone formedfrom a silicone hydrogel having a modulus of about of about 10,000 toabout 200,000 psi, or 15,000 psi to about 100,000 psi to correct opticaldefects with reduced or no need to maintain the lens rotationallyaligned if rotational alignment would normally be required. It should beappreciated that silicone hydrogels with higher modulus values willprovide greater design flexibility and allow for a thinner optical zone.

In order to realize this design, the optic zone 102 preferably comprisesa silicone hydrogel having a modulus of about 10,000 psi to about200,000 psi, or of about 15,000 to about 100,000 psi. Surprisingly,despite these very high moduli values, the silicone hydrogels alsocomprise water contents between about 10 wt % and 40 wt % or 10 wt % to30 wt %.

First Silicone Hydrogel Reactive Mixture

The silicone hydrogels of the present invention are formed from reactivemixtures comprising (a) at least one N-alkyl methacrylamide monomer, (b)at least one silicone-containing component, and (e) at least onecross-linking agent. The N-alkyl methacrylamide monomer has thestructure shown in Formula I:

wherein R′ is selected from linear, branched, or cyclic alkyl groupscontaining one to eight carbon atoms, benzyl or phenyl, any of which maybe un-substituted or substituted with additional functional groups suchas hydroxyl, amino, and the like.

R′ may also be selected from the group consisting of unsubstituted C₁-C₄alkyl groups.

When R′ is methyl, the N-alkyl methacrylamide monomer is N-methylmethacrylamide (NMMA).

The N-alkyl methacrylamide monomer may be present in the reactivemixture in concentrations between about 1 and about 50 weight percent,about 5 to about 50, about 7 to about 30, about 7 to about 25 or about 7to about 20 wt %, based upon all reactive components.

It has been surprisingly found that hydrogels made from reactivemixtures comprising at least one N-alkyl methacrylamide monomer and atleast one silicone containing component display significantly increasedmodulus, while still retaining water content values of greater than 10%or 15% water. The modulus values can range up to 200,000 psi. Despitetheir surprisingly increased modulus, the silicone hydrogels of thepresent invention are not brittle, and have acceptable % elongationvalues greater than 5%, or greater than 10%. These materials may be usedto create hybrid contact lenses, with rigid centers which retain theirshape when placed on eye, instead of vaulting over the cornea. Thiscreates a stiffer central optic zone relative to the peripheral zone ofthe contact lens. Stiffness is the modulus of the material, E,multiplied by the cube of thickness, t: Et³.

For contact lenses, as a lens gets thicker, especially beyond about 150or 200 microns, lens awareness increases. Thus, when creating a hybridlens, it may be desirable use materials having moduli greater than about1,000, 10,000 or 100,000. The at least one N-alkyl methacrylamidemonomer and siloxane groups on the at least one silicone containingcomponent appear to interact with each other to create hydrogels havingincreased modulus values compared to formulations without both the atleast one N-alkyl methacrylamide monomer and at least one siliconecontaining component.

The silicone-containing component may be a monomer or macromer and maycomprise at least one monovalent reactive group and at least onesiloxane group. The silicone-containing components may have at leastfour repeating siloxane units, which may be any of the groups definedbelow.

The silicone-containing component may also contain at least one fluorineatom. The silicone-containing component may be selected from thepolydisubstituted siloxane macromer of Formula II,

-   -   wherein:    -   at least one R¹⁸ is a monovalent reactive group, and the        remaining R¹⁸ are independently selected from    -   monovalent reactive groups, monovalent alkyl groups, or        monovalent aryl groups, any of the foregoing which may further        comprise functionality selected from hydroxy, amino, oxa,        carboxy, alkyl carboxy, alkoxy, amido, carbamate, carbonate,        halogen or combinations thereof;    -   fluoroalkyl alkyl or aryl groups; partially fluorinated alkyl or        aryl groups; halogens; linear, branched or cyclic alkoxy or        aryloxy groups; linear or branched polyethyleneoxyalkyl groups,        polypropyleneoxyalkyl groups, or        poly(ethyleneoxy-co-propyleneoxyalkyl groups; and    -   monovalent siloxane chains comprising between 1-100 siloxane        repeat units which may further comprise functionality selected        from alkyl, alkoxy, hydroxy, amino, oxa, carboxy, alkyl carboxy,        alkoxy, amido, carbamate, halogen or combinations thereof;        wherein n is 0 to 500 or 0 to 200, or 0 to 100, or 0 to 20,        where it is understood that when n is other than 0, n is a        distribution having a mode equal to a stated value.

In Formula II from one to three R¹⁸ may comprise monovalent reactivegroups.

Suitable monovalent alkyl and aryl groups include

-   -   unsubstituted and substituted monovalent linear, branched or        cyclic C₁ to C₁₆ alkyl groups, or unsubstituted monovalent C₁ to        C₆ alkyl groups, such as substituted and unsubstituted methyl,        ethyl, propyl, butyl,    -   substituted or unsubstituted C₆-C₁₄ aryl groups, or a        substituted or un-substituted C₆ aryl group, wherein the        substituents include amido, ether, amino, halo, hydroxyl,        carboxyl, carbonyl groups; or a phenyl or benzyl group,        combinations thereof and the like.

When one R¹⁸ is a monovalent reactive group, the additional siliconecontaining compounds may be selected from the polydisubstituted siloxanemacromer of Formulae IIIa or IIIb; the styryl polydisubstituted siloxanemacromer of Formula IVa or IVb or the carbosilane of Formula IVc:

wherein R¹ is a hydrogen atom or methyl;

Z is selected from O, N, S or NR₁CH₂CH₂O; when Z═O or S, R² is notrequired;

wherein j is a whole number between 1 and 20;

wherein R¹⁹ is

-   -   a substituted or unsubstituted C₁₋₆, C₁₋₄ or C₂₋₄ alkylene        segment (CH₂)_(r)        -   each methylene group may optionally be independently            substituted with ethers, amines, carbonyls, carboxylates,            carbamates and combinations thereof; or        -   an oxyalkylene segment (OCH₂)_(k) and        -   k is a whole number from one to three, or wherein R¹⁹ may be            a mixture of alkylene and oxyalkylene segments and the sum            of r and k is between 1 and 9;

wherein each R³ and R⁴ are independently a linear, branched, or cyclicalkyl group containing between one and six carbon atoms, a linear,branched, or cyclic alkoxy group containing between one and six carbonatoms, a linear or branched polyethyleneoxyalkyl group, a phenyl group,a benzyl group, a substituted or un-substituted aryl group, afluoroalkyl group, a partially fluorinated alkyl group, a perfluoroalkylgroup, a fluorine atom, or combinations thereof;

wherein R⁵ is a substituted or un-substituted linear or branched alkylgroup having 1 to eight carbon atoms, or 1 to 4 carbon atoms, or methylor butyl; or an aryl group, any of which may be substituted with one ormore fluorine atoms.

Non-limiting examples of polysiloxane macromers includemonomethacryloxypropyl terminated mono-n-butyl terminatedpolydimethylsiloxanes (mPDMS) as shown in Formula V wherein n is between3 and 15; monomethacryloxypropyl terminated mono-n-alkyl terminatedpolydimethylsiloxanes, mono-n-alkyl terminated, polydimethyl,polyethylene glycol siloxanes as shown in Formulae VIa and VIb wherein qis up to 50, 5 to 30 or 10-25; n¹ and n² are between 4 to 100; 4 to 50;or 4 to 25; n³ is 1-50, 1-20, or 1-10, and R² though R⁴ are as definedabove; q is up to 50, 5-30 or 10-25; and macromers having the chemicalstructures as shown in formulae VIIa through Xb, where n is between4-100, 4 and 20, or between 3 and 15, and R⁵ may be C1-C4 alkyl ormethyl or butyl.

Examples of suitable mono(meth)acryloxyalkylpolydisubstituted siloxanesinclude mono(meth)acryloxypropyl terminated mono-n-butyl terminatedpolydimethylsiloxane, mono(meth)acryloxypropyl terminated mono-n-methylterminated polydimethylsiloxane, mono(meth)acryloxypropyl terminatedmono-n-butyl terminated polydiethylsiloxane, mono(meth)acryloxypropylterminated mono-n-methyl terminated polydiethylsiloxane,mono(meth)acrylamidoalkylpolydialkylsiloxanes mono(meth)acryloxyalkylterminated mono-alkyl polydiarylsiloxanes, and mixtures thereof.

In Formula II, when n is zero, one or more R¹⁸ may comprise a monovalentreactive group, two or more R¹⁸ comprise tristriC₁₋₄alkylsiloxysilanegroups, monovalent siloxane chains comprising between 1-100, 1-10 or 1-5siloxane repeat units which may further comprise functionality selectedfrom alkyl, alkoxy, hydroxy, amino, oxa, carboxy, alkyl carboxy, alkoxy,amido, carbamate, halogen or combinations thereof; and the remaining R¹⁸are selected from monovalent alkyl groups having 1 to 16, 1 to 6 or 1-4carbon atoms. Non-limiting examples of silicone components include,3-methacryloxypropyltris(trimethylsiloxy)silane (TRIS),3-methacryloxypropylbis(trimethylsiloxy)methylsilane, and3-methacryloxypropylpentamethyl disiloxane.

The number of siloxane repeating units, n, may also be 2 to 50, 3 to 25,or 3 to 15; wherein at least one terminal R¹⁸ comprises a monovalentreactive group and the remaining R¹⁸ are selected from monovalent alkylgroups having 1 to 16 carbon atoms, or from monovalent alkyl groupshaving 1 to 6 carbon atoms. Silicone-containing compounds may alsoinclude those where n is 3 to 15, one terminal R¹⁸ comprises amonovalent reactive group, the other terminal R¹⁸ comprises a monovalentalkyl group having 1 to 6 carbon atoms and the remaining R¹⁸ comprisemonovalent alkyl group having 1 to 3 carbon atoms. Non-limiting examplesof silicone components include monomethacryloxypropyl n-butyl terminatedpolydimethylsiloxanes (M_(n)=800-1000), (mPDMS, as shown in V).

Formula II may also include compounds where n is 5 to 400 or from 10 to300, both terminal R¹⁸ comprise monovalent reactive groups and theremaining R¹⁸ are independently of one another selected from monovalentalkyl groups having 1 to 18 carbon atoms which may have ether linkagesbetween carbon atoms and may further comprise halogen.

One to four R¹⁸ in Formula II may comprise a vinyl carbonate or vinylcarbamate of Formula XI:

wherein: Y denotes O—, S— or NH—; R¹ denotes a hydrogen atom or methyl.The silicone-containing vinyl carbonate or vinyl carbamate monomersspecifically include:1,3-bis[4-(vinyloxycarbonyloxy)but-1-yl]tetramethyl-disiloxane;3-(vinyloxycarbonylthio) propyl-[tris(trimethylsiloxy)silane];3-[tris(trimethylsiloxy)silyl] propyl allyl carbamate;3-[tris(trimethylsiloxy)silyl] propyl vinyl carbamate;trimethylsilylethyl vinyl carbonate; trimethylsilylmethyl vinylcarbonate, and the crosslinking agent of Formula XII.

Where biomedical devices with moduli below about 200 psi are desired,only one R¹⁸ comprises a monovalent reactive group and no more than twoof the remaining R¹⁸ groups comprise monovalent siloxane groups.

Another suitable silicone-containing macromer is compound of FormulaXIII in which the sum of x and y is a number in the range of 10 to 30.The silicone containing macromer of Formula XXIII is formed by thereaction of fluoroether, hydroxy-terminated polydimethylsiloxane,isophorone diisocyanate and isocyanatoethylmethacrylate.

The non-hydroxyl containing silicone-containing component may beselected from non-hydroxyl containing acrylamide silicones of U.S. Pat.No. 8,415,405. Other silicone components suitable for use in thisinvention include those described is WO 96/31792 such as macromerscontaining polysiloxane, polyalkylene ether, diisocyanate,polyfluorinated hydrocarbon, polyfluorinated ether and polysaccharidegroups. Another class of suitable silicone-containing componentsincludes silicone-containing macromers made via GTP, such as thosedisclosed in U.S. Pat. Nos. 5,314,960, 5,331,067, 5,244,981, 5,371,147,and 6,367,929. U.S. Pat. Nos. 5,321,108, 5,387,662, and 5,539,016describe polysiloxanes with a polar fluorinated graft or side grouphaving a hydrogen atom attached to a terminal difluoro-substitutedcarbon atom. US 2002/0016383 describes hydrophilic siloxanylmethacrylates containing ether and siloxanyl linkages and crosslinkablemonomers containing polyether and polysiloxanyl groups. Any of theforegoing polysiloxanes can also be used as the silicone-containingcomponent in this invention.

The non-hydroxyl containing silicone component may be selected from thegroup consisting of monomethacryloxypropyl terminated, mono-n-alkylterminated linear polydisubstituted siloxane;methacryloxypropyl-terminated linear polydisubstituted siloxane; andmixtures thereof.

The non-hydroxyl containing silicone component may also be selected frommonomethacrylate terminated, C₁-C₄ alkyl terminated, linearpolydimethylsiloxanes; and mixtures thereof.

In some instances, the non-hydroxyl functionalized silicone-containingcomponent may be used in amounts up to about 10 wt %. Examples includethose selected from mPDMS of Formula XXII where R⁵ is methyl or butyl,compounds of Formulae XXVIa, XVIIb through XVIIIb, XX, XXIa, XXIb andthe macromers shown in Formula XXV or XXVI where n is n is 1-50 and m is1-50, 1-20 or 1-10:

Specific examples of non-hydroxyl functionalized silicone-containingcomponents include mPDMS of Formula VIa, compounds of Formulae Vila orb, or VIII where R¹ is methyl and R⁵ is selected from methyl or butyland the macromers shown in Formula XIV where n is 1-50 or 4-40, 4-20.

Specific examples of silicone containing crosslinkers includebismethacryloxypropyl polydimethyl siloxane, where n may be 4-200, or4-150, and the following compounds of Formula XVIa-XVIc, where n¹ and n²are independently selected from 4 to 100; 4 to 50; or 4 to 25; n³ is1-50, 1-20 or 1-10, m is 1-100, 1-50, 1-20 or 1-10, and q is up to 50,5-30 or 10-25.

The non-hydroxyl containing silicone component may have an averagemolecular weight of from about 400 to about 4000 Daltons.

When Z is O, the silicone containing component may be amonomethacryloxypropyl terminated mono-n-butyl terminatedpolydimethylsiloxanes (mPDMS) as shown in Formula VI wherein n isbetween 3 and 15; monomethacryloxypropyl terminated mono-n-alkylterminated polydimethylsiloxanes as shown in Formula VIa wherein n isbetween 3 and 15 and R is a linear, branched, or cyclic alkyl groupcontaining between 1 and 8 carbon atoms; and macromers having thechemical structures as shown in Formulae Vila through XIIc, or VIIIwhere n is between 4 and 20, or between, 3 and 15, 3-30, 3-25, 3-20 or3-15.

When X is N, further examples of polysiloxane macromers includeMono(meth)acrylamidoalkylpolydialkylsiloxanes may be selected from thosedisclosed in U.S. Pat. No. 8,415,405, and those shown in Formulae XIII,mono(meth)acrylamidoalkyl polydimethylsiloxanes, such as those inFormulae XIX-XXIII, and N-(2,3-dihydroxypropane)-N′-(propyltetra(dimethylsiloxy) dimethylbutylsilane)acrylamide:

Examples of styryl monomers include tris(trimethylsiloxy)silyl styrene.Examples of styryl macromers are shown below in chemical formulae XXIVthrough XIX, wherein n is as defined above.

The length of the silicone chain may have an impact on the modulus ofthe resulting silicone hydrogel and may be adjusted along with the othercomponents of the reactive mixture to achieve the desired balance ofphysical and mechanical properties. For instance, the amounts of NMMAand the length of the silicone chain may be chosen to attain a watercontent of the silicone hydrogel that moderates stiffness and increaseselongation to break concurrently. As the polydialkylsiloxane chainlength increases, modulus will decrease and elongation to break willincrease. Polydialkylsiloxane chain lengths between 1 and 20, 1 and 15,3-30, 3-25, 3-20 or 3-15 may be selected.

The silicone-containing component may further includesilicone-containing monomers with branched siloxane groups. Examplesinclude tris(trimethylsiloxy)silylstyrene (Styryl-TRIS),3-tris(trimethylsiloxy)silylpropyl methacrylate (TRIS),N-[3-tris(trimethylsiloxy)silyl]-propyl acrylamide (TRIS-Am, FormulaXXI), 2-hydroxy-3-[3-methyl-3,3-di(trimethylsiloxy)silylpropoxy]-propylmethacrylate (SiMAA), and other bulky silicone monomers, such as thosein Formulae XXa through XXe, wherein R⁸ and R⁹ is independently linear,branched, or cyclic alkyl groups containing between one and eight carbonatoms, or are trimethylsiloxy groups.

The aforementioned macromers have methacrylate, acrylamide, ormethacylamide reactive groups. These reactive groups may be replacedwith any other reactive group capable of undergoing free radicalpolymerization, such as acrylates, styrenes, vinyl ethers,N-vinyllactams, N-vinylamides, N-vinylimides, N-vinylureas,O-vinylcarbamates, O-vinylcarbonates, and other vinyl compounds. Wheremoduli greater than about 5000 psi are desired, monomers and macromerswith styryl reactive groups are beneficially included. Alternativesilicone-containing components suitable for use include those describedin WO 96/31792 and U.S. Pat. No. 5,314,960, U.S. Pat. No. 5,331,067,U.S. Pat. No. 5,244,981, U.S. Pat. No. 5,371,147, U.S. Pat. No.6,367,929, U.S. Pat. No. 5,321,108, U.S. Pat. No. 5,387,662, U.S. Pat.No. 5,539,016, U.S. Pat. No. 6,867,245, and others will be apparent toone skilled in the art.

Hydroxyl-Containing Silicone Component

The silicone containing component may also comprise one or morehydroxyl-containing silicone component. Hydroxyl-containing siliconecomponents may help to compatibilize high concentrations of siliconecontaining components with hydrophilic components, including polymerichydrophilic components, and silicone components having bulky siloxanegroups or longer chains of repeating siloxane units. Hydroxyl-containingsilicone components include hydroxyl containing silicone monomers andmacromers. The Hydroxyl-containing silicone components may have 4 to200, 4-100 or 4-20 siloxane repeating units and may be monofunctional ormultifunctional.

Hydroxyl-containing silicone components having 4 polysubstitutedsiloxane repeating units in the siloxane chain are not a distributionand have four repeating units in each monomer. For allhydroxyl-containing silicone components having more than fourpolydisubstituted siloxane repeating units in the siloxane chain thenumber of repeating units is a distribution, with the peak of thedistribution centered around the listed number of repeat units.

Examples of hydroxyl-containing silicone monomers include propenoicacid-2-methyl-2-hydroxy-3-[3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]-1-disiloxanyl]propoxy]propylester (“SiGMA”), and2-hydroxy-3-methacryloxypropyloxypropyl-tris(trimethylsiloxy)silane, andcompounds of Formula XXd.

The hydroxyl-containing silicone components may be selected frommonofunctional hydroxyl substituted poly(disubstituted siloxane)s ofFormula XXI:

-   -   wherein Z is selected from O, N, S or NR¹CH₂CH₂O, when Z is O or        S R² is not present;    -   R¹ is independently H or methyl;    -   R², R³ and R⁴ are independently a linear, branched, or cyclic        alkyl group containing one to eight carbon atoms, any of which        may be further substituted with at least one hydroxy group, and        which may be optionally substituted with amide, ether, and        combinations thereof; R³ and R⁴ may be independently selected        from methyl, ethyl or phenyl, or may be methyl;    -   n is the number of siloxane units and is from 4 to 8 for the        first monofunctional hydroxyl substituted poly(disubstituted        siloxane) monomer, and    -   R⁵ is selected from straight or branched C₁ to C₅ alkyl groups,        which may be optionally substituted with one or more hydroxyl,        amide, ether, and    -   combinations thereof. R⁵ may be straight or branched C₄ alkyl,        either of which may optionally be substituted with hydroxyl, or        may be methyl.

Examples of monofunctional hydroxyl containing silicone componentsinclude mono-(2-hydroxy-3-methacryloxypropyl)-propyl ether terminatedmono-n-butyl terminated polydimethylsiloxanes (OH-mPDMS) as shown inFormula) XXIIa wherein n is between 4 and 30, 4-8 or 10-20; andpolydimethylsiloxanes having the chemical structures as shown inFormulae XXIIb through XXIIId, where n is between 4 and 30, 4 and 8 or10 and 20; n¹ n², and n³ are independently between 4 to 100; 4 to 50; 4to 25; R⁵ is selected from straight or branched C₁ to C₈ alkyl groups,which may be optionally substituted with one or more hydroxyl, amide,ether, polyhydroxyl groups selected from straight or branched C₁ to C₈groups having a formula of C_(f)H_(g)(OH)_(h) wherein f=1-8 and g+h=2f+1and cyclic C₁ to C₈ groups having a formula of C_(f)H_(g)(OH)_(h)wherein f=1-8 and g+h=2f−1, and combinations thereof; or R⁵ may beselected from methyl, butyl or hydroxyl substituted C₂-C₅ alkyl,including hydroxyl ethyl, hydroxyl propyl, hydroxyl butyl, hydroxylpentyl and 2,3-dihydroxypropyl, and polycarbosiloxanes of Formula XXIVwhere a and b are between 4-100 or 4-8 and c is 4-8 for the firsthydroxyl-containing silicone component and R¹ and R⁵ are as definedabove.

The hydroxyl-containing silicone component may also be selected frommultifunctional hydroxyl substituted, poly(disubstituted siloxane) ofFormula XXV having 10 to 500, or 10 to 200, or 10 to 100 siloxanerepeating units, and mixtures thereof:

wherein in Formula XXV, Z is selected from O, N, S or NR¹CH₂CH₂O;wherein R¹ is independently a hydrogen atom or methyl group; for Z═O andS, R² is not required;

-   -   R², R⁶, R⁷, R⁸, R⁹, R¹⁹ are independently selected from the        group consisting of a hydrogen atom or any of the substituents        defined for R¹¹ through R¹⁴;    -   R¹¹, R¹², R¹³, R¹⁴ are independently selected from the group        consisting of a linear, branched, or cyclic alkyl group        containing one to eight carbon atoms, any of which may be        further substituted with at least one hydroxy group, amido,        ether, amino, carboxyl, carbonyl groups and combinations; a        linear or branched alkyleneoxy group, specifically ethyleneoxy        groups, [CH₂CH₂O]_(p) wherein p is between 1 and 200, or 1 and        100, or 1 and 50, or 1 and 25, or 1 and 20, optionally        substituted with one or more hydroxyl, amino, amido, ether,        carbonyl, carboxyl, and combinations thereof;        -   a C₁-C₆ linear or branched fluoroalkyl groups optionally            substituted with one or more hydroxyl, amino, amido, ether,            carbonyl, carboxyl, and combinations thereof;        -   a substituted or un-substituted aryl groups, specifically            phenyl groups, wherein the substituents are selected from            halogen, hydroxyl, alkoxy, alkylcarbonyl, carboxy, and            linear or branched or cyclic alkyl groups which may be            further substituted with halogen, hydroxyl, alkoxy,            alkylcarbonyl, and carboxyl groups, and combinations            thereof; and        -   a, b, c, x, y and z are independently between 0 and 100,            between 0 and 50, between 0 and 20, between 0 and 10, or            between 0 and 5; and        -   n is the number of siloxane repeating units and is from 10            to 500; 10 to 200; 10 to 100; 10 to 50; 10 to 20.

Examples of multifunctional hydroxyl containing silicones includeα-(2-hydroxy-1-methacryloxypropyloxypropyl)-w-butyl-decamethylpentasiloxaneand the difunctional polysiloxanes of Formulae XXVI or XXVII:

Wherein the substituents are as defined above;

wherein

R¹ is independently a hydrogen atom or methyl group;

R¹⁵ and R¹⁶ are independently a linear, branched, or cyclic alkyl groupcontaining one to eight carbon atoms, any of which may be furthersubstituted with at least one hydroxy group, amido, ether, amino,carboxyl, carbonyl groups and combinations thereof; or are independentlyselected from unsubstituted C₁₋₄ alkyl groups and C₁₋₄ alkyl groupssubstituted with hydroxyl or ether; or are selected from methyl, ethylor —(CH₂CH₂O)_(n3)OCH₃;

n¹ and n² are independently selected from is 4 to 100; 4 to 50; or 4 to25 and n³ is 1-50, 1-20, and 1-10

At least one silicone-containing component is present in the reactivemixture in an amount sufficient to provide the desired modulus andoxygen permeability of the silicone hydrogel. It has been found that theN-alkyl methacrylamides provide a surprising increase in modulus whenincluded in formulations also comprising a silicone-containingcomponent. This increase in modulus is not observed in conventionalhydrogel formulations. The silicone-containing component may be includedin the reactive mixture in amounts from about 20 to about 60 weight %,or from about 30 to about 55 weight %, from about 30 weight % to about50 weight %, from about 50 weight % to about 60 weight %, all based uponthe total weight of all of the reactive components.

It may also be desirable for the resulting silicone hydrogel to exhibitoxygen permeability greater than about 50 barrers, between about 50barrers and about 200 barrers; between about 70 barrers and about 150barrers; or between about 80 barrers and about 150 barrers.

Cross-Linking Agent

The silicone hydrogels of the present invention include at least onecross-linking agent. A variety of cross-linking agents may be used,including silicone-containing and non-silicone containing cross-linkingagents, and mixtures thereof. Non-silicone-containing cross-linkingagents include ethylene glycol dimethacrylate (EGDMA), diethyleneglycoldimethacrylate, trimethylolpropane trimethacrylate (TMPTMA),tetraethylene glycol dimethacrylate (TEGDMA), triallyl cyanurate (TAC),glycerol trimethacrylate, 1,3-propanediol dimethacrylate;2,3-propanediol dimethacrylate; 1,6-hexanediol dimethacrylate;1,4-butanediol dimethacrylate, methacryloxyethyl vinylcarbonate(HEMAVc), allylmethacrylate, methylene bisacrylamide (MBA), polyethyleneglycol dimethacrylate (wherein the polyethylene glycol preferably has amolecular weight up to 5,000 Daltons). Any of the above disclosedmultifunctional silicone-containing components may be used ascross-linking agents.

Other cross-linking agents will be known to one skilled in the art andmay be used to make the silicone hydrogel of the present invention.

The non-silicone containing crosslinking agents are used in amounts fromabout 0.5 weight % to about 20 weight %, 3 weight % to 20 weight % orfrom about 3 weight % to about 15 weight %, all based upon the totalweight of all of the reactive components. The exact amounts varydepending on the mechanical property targets and the other reactivecomponents in the reactive mixture. In other units, the cross-linkingagent may vary from about 16 mmoles in 100 grams of reactive mixture toabout 30 mmole in 100 grams of reactive mixture, and preferably between16 mmoles/100 grams and 25 mmoles/100 grams of reactive mixture. It maybe desirable to select the crosslinking agents which have reactivegroups with similar reactivity rates with those of the other componentsto form the silicone hydrogel networks. Thus it may be desirable toselect crosslinking agents with at least one reactive group which is thesame as the reactive groups included in the other reactive components.The structure and morphology of the resulting silicone hydrogel may alsobe influenced by the diluent(s) and cure conditions used.

Multifunctional silicone-containing components, including macromers mayalso be included to further increase the modulus and retain tensilestrength. The silicone containing crosslinking agents may be used aloneor in combination with other cross-linking agents. An example of asilicone containing monomer which can act as a crosslinking agent and,when present, does not require the addition of a crosslinking monomer tothe reaction mixture includes α,ω-bismethacryloypropylpolydimethylsiloxane.

When silicone cross-linking agents are used in the formulation, limitingthe number of siloxane repeating units in the silicone cross-linkingagent between 5 and 200, 5 and 150, 5 and 120 allows the retention ofmodulus values in excess of 15,000 psi, without significantly impactingother properties such as oxygen permeability, and elongation. Whenmoduli over 15,000 psi are desired, silicone cross-linking agents may beincluded in amounts between 0 to about 25 weight percent, or betweenabout 10 weight percent and 20 weight percent, all based upon the totalweight of all of the reactive components.

Non-limiting examples of silicone cross-linking agents are shown inFormulae XII, XIII, XVIa-XVIIc, above and the following chemicalFormulae XXVI through XXXVII, wherein n is between 1 and 200, preferablyn is between 50 and 150, more preferably between 50 and 100, and mostpreferably n is between 10 and 50.

The aforementioned silicone cross-linking agents may also have acrylate,methacrylate, O-vinylcarbonate, or methacylamide reactive groups. Thesereactive groups may be replaced with any other reactive group capable ofundergoing free radical polymerization, such as, styrenes, vinyl ethers,N-vinyllactams, N-vinylamides, N-vinylimides, N-vinylureas,O-vinylcarbamates, and other vinyl compounds. In some embodiments,silicone cross-linking agents with styryl reactive groups are preferred.

Cross-linking agents that have rigid chemical structures and reactivegroups that undergo free radical polymerization may also be used.Non-limiting examples of suitable rigid structures include cross-linkingagents comprising phenyl and benzyl ring, such are 1,4-phenylenediacrylate, 1,4-phenylene dimethacrylate,2,2-bis(4-methacryloxyphenyl)-propane,2,2-bis[4-(2-acryloxyethoxy)phenyl]propane,2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane, and4-vinylbenzyl methacrylate, and combinations thereof. Rigid crosslinkingagents may be included in amounts between about 2 and about 15, or 2-10,3-7 based upon the total weight of all of the reactive components.

The more NMMA used, the more crosslinker can be used, while stillreaching target water contents, and modulus.

The physical and mechanical properties of the silicone hydrogels of thepresent invention may be optimized for a particular use by adjusting thecomponents in the reactive mixture. It is a benefit of the presentinvention that the desired moduli may be achieved using monofunctionalsilicone-containing components.

Hydrophilic Monomer

The silicone hydrogels of the present invention may further include oneor more hydrophilic monomer. Hydrophilic monomers can be any of thehydrophilic monomers known to be useful to make hydrogels. Classes ofsuitable hydrophilic monomers include acrylic-containing monomers andvinyl-containing monomers. Examples of suitable families of hydrophilicmonomers include N-vinyl amides, N-vinylimides, N-vinyl lactams,hydrophilic (meth)acrylates, (meth)acrylamides, hydrophilic styrenes,vinyl ethers, O-vinyl carbonates, O-vinyl carbamates, N-vinyl ureas,other hydrophilic vinyl compounds and mixtures thereof.

The hydrophilic monomers that may be used to make the polymers of thisinvention have at least one polymerizable double bond and at least onehydrophilic functional group. Such hydrophilic monomers may themselvesbe used as crosslinking agents, however, where hydrophilic monomershaving more than one polymerizable functional group are used, theirconcentration should be limited as discussed above to provide a contactlens having the desired modulus. The term “vinyl-type” or“vinyl-containing” monomers refer to monomers containing the vinylgrouping (—CH═CH₂) and are generally highly reactive. Such hydrophilicvinyl-containing monomers are known to polymerize relatively easily.

“Acrylic-type” or “acrylic-containing” monomers are those monomerscontaining an acrylic group (CH₂═CRCOX) wherein R is H or CH₃, and X isO or N, which are also known to polymerize readily, such as N,N-dimethylacrylamide (DMA), 2-hydroxyethyl methacrylamide, polyethyleneglycolmonomethacrylate, methacrylic acid, acrylic acid, mixtures thereof andthe like.

Hydrophilic monomers with at least one hydroxyl group (hydroxylalkylmonomer) may be used. The hydroxyl alkyl group may be selected fromC₂-C₄ mono or dihydroxy substituted alkyl, and poly(ethylene glycol)having 1-10 repeating units; or is selected from 2-hydroxyethyl,2,3-dihydroxypropyl, or 2-hydroxypropyl, and combinations thereof.

Examples of hydroxyalkyl monomers include 2-hydroxyethyl (meth)acrylate(HEMA), 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate,2,3-dihydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate,3-hydroxybutyl (meth)acrylate, 1-hydroxypropyl 2-(meth)acrylate,2-hydroxy-2-methyl-propyl (meth)acrylate, 3-hydroxy-2,2-dimethyl-propyl(meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl(meth)acrylamide, N-(2-hydroxypropyl) (meth)acrylamide,N,N-bis(2-hydroxyethyl) (meth)acrylamide, N,N-bis(2-hydroxypropyl)(meth)acrylamide, N-(3-hydroxypropyl) (meth)acrylamide,2,3-dihydroxypropyl (meth)acrylamide, glycerol (meth)acrylate,polyethyleneglycol monomethacrylate, and mixtures thereof.

The hydroxyalkyl monomer may also be selected from the group consistingof 2-hydroxyethyl methacrylate, glycerol methacrylate, 2-hydroxypropylmethacrylate, hydroxybutyl methacrylate, 3-hydroxy-2,2-dimethyl-propylmethacrylate, and mixtures thereof.

The hydroxyalkyl monomer may comprise 2-hydroxyethyl methacrylate,3-hydroxy-2,2-dimethyl-propyl methacrylate, hydroxybutyl methacrylate orglycerol methacrylate.

When hydrophilic polymers in quantities great than about 3 wt % aredesired, Hydroxyl containing (meth)acrylamides are generally toohydrophilic to be included as compatibilizing hydroxyalkyl monomers, andhydroxyl containing (meth)acrylates may be included in the reactivemixture and the lower amount of hydroxyalkyl monomers may be selected toprovide a haze value to the final lens of less than about 50% or lessthan about 30%.

It will be appreciated that the amount of hydroxyl component will varydepending upon a number of factors, including, the number of hydroxylgroups on the hydroxyalkyl monomer, the amount, molecular weight andpresence of hydrophilic functionality on the silicone containingcomponents. The hydrophilic hydroxyl component may be present in thereactive mixture in amounts up to about 15%, up to about 10 wt %,between about 3 and about 15 wt % or about 5 and about 15 wt %.

Hydrophilic vinyl-containing monomers which may be incorporated into thehydrogels include monomers such as hydrophilic N-vinyl lactam andN-vinyl amide monomers including: N-vinyl pyrrolidone (NVP),N-vinyl-2-piperidone, N-vinyl-2-caprolactam,N-vinyl-3-methyl-2-caprolactam, N-vinyl-3-methyl-2-piperidone,N-vinyl-4-methyl-2-piperidone, N-vinyl-4-methyl-2-caprolactam,N-vinyl-3-ethyl-2-pyrrolidone, N-vinyl-4,5-dimethyl-2-pyrrolidone,N-vinyl acetamide (NVA), N-vinyl-N-methylacetamide (VMA),N-vinyl-N-ethyl acetamide, N-vinyl-N-ethyl formamide, N-vinyl formamide,N-vinyl-N-methylpropionamide, N-vinyl-N-methyl-2-methylpropionamide,N-vinyl-2-methylpropionamide, N-vinyl-N,N′-dimethylurea,1-methyl-3-methylene-2-pyrrolidone, 1-methyl-5-methylene-2-pyrrolidone,5-methyl-3-methylene-2-pyrrolidone; 1-ethyl-5-methylene-2-pyrrolidone,N-methyl-3-methylene-2-pyrrolidone, 5-ethyl-3-methylene-2-pyrrolidone,1-N-propyl-3-methylene-2-pyrrolidone,1-N-propyl-5-methylene-2-pyrrolidone,1-isopropyl-3-methylene-2-pyrrolidone,1-isopropyl-5-methylene-2-pyrrolidone, N-vinyl-N-ethyl acetamide,N-vinyl-N-ethyl formamide, N-vinyl formamide, N-vinyl isopropylamide,N-vinyl caprolactam, N-carboxyvinyl-β-alanine (VINAL),N-carboxyvinyl-α-alanine, N-vinylimidazole, and mixtures thereof.

Hydrophilic O-vinyl carbamates and O-vinyl carbonates monomersincluding: N-2-hydroxyethyl vinyl carbamate and N-carboxy-β-alanineN-vinyl ester. Further examples of the hydrophilic vinyl carbonate orvinyl carbamate monomers are disclosed in U.S. Pat. No. 5,070,215, andthe hydrophilic oxazolone monomers are disclosed in U.S. Pat. No.4,910,277.

Vinyl carbamates and carbonates, including N-2-hydroxyethyl vinylcarbamate, N-carboxy-β-alanine N-vinyl ester,

Other hydrophilic vinyl monomers, including vinylimidazole, ethyleneglycol vinyl ether (EGVE), di(ethylene glycol) vinyl ether (DEGVE),allyl alcohol, 2-ethyl oxazoline, vinyl acetate, acrylonitrile, andmixtures thereof.

(Meth)acrylamide monomers may also be included as hydrophilic monomers.Examples include N—N-dimethylacrylamide, acrylamide,N,N-bis(2-hydroxyethyl)acrylamide, acrylonitrile, N-isopropylacrylamide, N,N-dimethylaminopropyl(meth)acrylamide, and any of thehydroxyl functional (meth)acrylamides listed above.

The hydrophilic monomers which may be incorporated into the polymersdisclosed herein may be selected from N,N-dimethyl acrylamide (DMA),2-hydroxyethyl acrylamide, 2-hydroxyethyl methacrylamide,N-hydroxypropyl methacrylamide, bishydroxyethyl acrylamide,2,3-dihydroxypropyl (meth)acrylamide, N-vinylpyrrolidone (NVP),N-vinyl-N-methyl acetamide, N-vinyl methacetamide (VMA), andpolyethyleneglycol monomethacrylate.The hydrophilic monomers may be selected from DMA, NVP, VMA, NVA, andmixtures thereof.

The hydrophilic monomers of the present invention may be macromers oflinear or branched poly(ethylene glycol), poly(propylene glycol), orstatistically random or block copolymers of ethylene oxide and propyleneoxide. The macromer of these polyethers has one reactive group.Non-limiting examples of such reactive groups are acrylates,methacrylates, styrenes, vinyl ethers, acrylamides, methacrylamides, andother vinyl compounds. In one embodiment, the macromer of thesepolyethers comprises acrylates, methacrylates, acrylamides,methacrylamides, and mixtures thereof. Other suitable hydrophilicmonomers will be apparent to one skilled in the art.

The hydrophilic monomers may also comprise charged monomers includingbut not limited to acrylic acid, methacrylic acid, 3-acrylamidopropionicacid (ACA1), 4-acrylamidobutanoic acid, 5-acrylamidopentanoic acid(ACA2), 3-acrylamido-3-methylbutanoic acid (AMBA),N-vinyloxycarbonyl-α-alanine, N-vinyloxycarbonyl-6-alanine (VINAL),combinations thereof and the like.

The hydrophilic monomers may be selected from N, N-dimethyl acrylamide(DMA), N-vinylpyrrolidone (NVP), 2-hydroxyethyl methacrylate (HEMA),N-vinyl methacetamide (VMA), and N-vinyl N-methyl acetamide (NVA),N-hydroxypropyl methacrylamide, mono-glycerol methacrylate,2-hydroxyethyl acrylamide, 2-hydroxyethyl methacrylamide,bishydroxyethyl acrylamide, 2,3-dihydroxypropyl (meth)acrylamide andmixtures thereof. The hydrophilic monomers may be selected from DMA,NVP, HEMA, VMA, NVA, and mixtures thereof.

The hydrophilic monomer(s) (including the hydroxyl alkyl monomers) maybe present in amounts up to about 60 wt %, between about 1 to about 60weight %, between about 5 to about 50 weight %, or about 5 to about 40weight %, based upon the weight of all reactive components.

The silicone hydrogels of the present invention may further comprise atleast one wetting agent. As used herein, wetting agents are hydrophilicpolymers having a weight average molecular weight greater than about5,000 Daltons, between about 150,000 Daltons to about 2,000,000 Daltons;between about 300,000 Daltons to about 1,800,000 Daltons; or betweenabout 500,000 Daltons to about 1,500,000 Daltons.

The amount of wetting agent added to the reactive mixtures of thepresent invention may be varied depending on the other components usedand the desired properties of the resulting silicone hydrogel. Whenpresent, the internal wetting agents in reactive mixtures may beincluded in amounts from about 1 weight percent to about 20 weightpercent; from about 2 weight percent to about 15 percent, or from about2 to about 12 percent, all based upon the total weight of all of thereactive components.

Wetting agents include but are not limited to homopolymers,statistically random copolymers, diblock copolymers, triblockcopolymers, segmented block copolymers, graft copolymers, and mixturesthereof. Non-limiting examples of internal wetting agents arepolyamides, polyesters, polylactones, polyimides, polylactams,polyethers, polyacids homopolymers and copolymers prepared by the freeradical polymerization of suitable monomers including acrylates,methacrylates, styrenes, vinyl ethers, acrylamides, methacrylamides,N-vinyllactams, N-vinylamides, 0-vinylcarbamates, 0-vinylcarbonates, andother vinyl compounds. The wetting agents may be made from anyhydrophilic monomer, including those listed herein.

The wetting agents may include acyclic polyamides comprise pendantacyclic amide groups and are capable of association with hydroxylgroups. Cyclic polyamides comprise cyclic amide groups and are capableof association with hydroxyl groups.

Examples of suitable acyclic polyamides include polymers and copolymerscomprising repeating units of Formula XXXVII or Formula XXXVIII:

wherein X is a direct bond, —(CO)—, or —(CO)—NHR^(e)—, wherein R^(e) isa C₁ to C₃ alkyl group; R^(a) is selected from H, straight or branched,substituted or unsubstituted C₁ to C₄ alkyl groups; R^(b) is selectedfrom H, straight or branched, substituted or unsubstituted C₁ to C₄alkyl groups, amino groups having up to two carbon atoms, amide groupshaving up to four carbon atoms, and alkoxy groups having up to twocarbon groups; R^(c) is selected from H, straight or branched,substituted or unsubstituted C₁ to C₄ alkyl groups, or methyl, ethoxy,hydroxyethyl, and hydroxymethyl; R^(d) is selected from H, straight orbranched, substituted or unsubstituted C₁ to C₄ alkyl groups; or methyl,ethoxy, hydroxyethyl, and hydroxymethyl wherein the number of carbonatoms in R^(a) and R^(b) taken together is 8 or less, including 7, 6, 5,4, 3, or less, and wherein the number of carbon atoms in R^(c) and R^(d)taken together is 8 or less, including 7, 6, 5, 4, 3, or less. Thenumber of carbon atoms in R^(a) and R^(b) taken together may be 6 orless or 4 or less. The number of carbon atoms in R^(c) and R^(d) takentogether may be 6 or less. As used herein substituted alkyl groupsinclude alkyl groups substituted with an amine, amide, ether, hydroxyl,carbonyl, carboxy groups or combinations thereof.

R^(a) and R^(b) can be independently selected from H, substituted orunsubstituted C₁ to C₂ alkyl groups. X may be a direct bond, and R^(a)and R^(b) may be independently selected from H, substituted orunsubstituted C₁ to C₂ alkyl groups.

R^(c) and R^(d) can be independently selected from H, substituted orunsubstituted C₁ to C₂ alkyl groups, methyl, ethoxy, hydroxyethyl, andhydroxymethyl.

The acyclic polyamides of the present invention may comprise a majorityof the repeating unit of Formula XXXVII or Formula XXXVIII, or theacyclic polyamides can comprise at least about 50 mole % of therepeating unit of Formula XXXVII or Formula XXXVIII, including at leastabout 70 mole %, and at least 80 mole %.

Specific examples of repeating units of Formula XXXVII or FormulaXXXVIII include repeating units derived from N-vinyl-N-methylacetamide,N-vinylacetamide, N-vinyl-N-methylpropionamide,N-vinyl-N-methyl-2-methylpropionamide, N-vinyl-2-methyl-propionamide,N-vinyl-N,N′-dimethylurea, N, N-dimethylacrylamide, methacrylamide andacyclic amides of structures (C) and (D):

Examples of suitable cyclic amides that can be used to form the cyclicpolyamides of include α-lactam, β-lactam, γ-lactam, δ-lactam, andε-lactam. Examples of suitable cyclic polyamides include polymers andcopolymers comprising repeating units of Formula XLI:

wherein f is a number from 1 to 10, X is a direct bond, —(CO)—, or—(CO)—NH—Re, wherein Re is a C1 to C3 alkyl group. In Formula XLI, f maybe 8 or less, including 7, 6, 5, 4, 3, 2, or 1. In Formula E, f may be 6or less, including 5, 4, 3, 2, or 1, or may be from 2 to 8, including 2,3, 4, 5, 6, 7, or 8, or may be 2 or 3.

When X is a direct bond, f may be 2. In such instances, the cyclicpolyamide may be polyvinylpyrrolidone (PVP).

The cyclic polyamides of the present invention may comprise 50 mole % ormore of the repeating unit of Formula E, or the cyclic polyamides cancomprise at least about 50 mole % of the repeating unit of Formula E,including at least about 70 mole %, and at least about 80 mole %.

Specific examples of repeating units of Formula XLI include repeatingunits derived from N-vinylpyrrolidone, which forms PVP homopolymers andvinylpyrrolidone copolymers or N-vinylpyrrolidone substituted withhydrophilic substituents such as phosphoryl choline.

The polyamides may also be copolymers comprising cyclic amide, acyclicamide repeating units or copolymers comprising both cyclic and acyclicamide repeating units. Additional repeating units may be formed frommonomers selected from hydroxyalkyl(meth)acrylates, alkyl(meth)acrylatesor other hydrophilic monomers and siloxane substituted acrylates ormethacrylates. Any of the monomers listed as suitable hydrophilicmonomers may be used as comonomers to form the additional repeatingunits. Specific examples of additional monomers which may be used toform polyamides include 2-hydroxyethylmethacrylate, vinyl acetate,acrylonitrile, hydroxypropyl methacrylate, 2-hydroxyethyl acrylate,methyl methacrylate and hydroxybutyl methacrylate, GMMA, PEGS, and thelike and mixtures thereof. Ionic monomers may also be included. Examplesof ionic monomers include acrylic acid, methacrylic acid,2-methacryloyloxyethyl phosphorylcholine,3-(dimethyl(4-vinylbenzyl)ammonio)propane-1-sulfonate (DMVBAPS),3-((3-acrylamidopropyl)dimethylammonio)propane-1-sulfonate (AMPDAPS),3-((3-methacrylamidopropyl)dimethylammonio)propane-1-sulfonate(MAMPDAPS),3-((3-(acryloyloxy)propyl)dimethylammonio)propane-1-sulfonate (APDAPS),methacryloyloxy)propyl)dimethylammonio)propane-1-sulfonate (MAPDAPS).

The reactive monomer mixture may comprise both an acyclic polyamide anda cyclic polyamide or copolymers thereof. The acyclic polyamide can beany of those acyclic polyamides described herein or copolymers thereof,and the cyclic polyamide can be any of those cyclic polyamides describedherein or copolymers thereof. The polyamide may be selected from thegroup polyvinylpyrrolidone (PVP), polyvinylmethyacetamide (PVMA),polydimethylacrylamide (PDMA), polyvinylacetamide (PNVA),poly(hydroxyethyl(meth)acrylamide), polyacrylamide, and copolymers andmixtures thereof.

The wetting agents may be made from DMA, NVP, HEMA, VMA, NVA, andcombinations thereof. The wetting agents may also be reactivecomponents, as defined herein, by having reactive groups, for example,made by the acylation reaction between pendant hydroxyl groups on HEMArepeating units of an internal wetting agent and methacryloyl chlorideor methacryloyl anhydride. Other methods of functionalization will beapparent to one skilled in the art.

Such internal wetting agents are disclosed in U.S. Pat. No. 6,367,929,U.S. Pat. Nos. 6,822,016, 7,052,131, U.S. Pat. No. 7,666,921, U.S. Pat.No. 7,691,916, U.S. Pat. No. 7,786,185, U.S. Pat. No. 8,022,158, andU.S. Pat. No. 8,450,387.

The silicone hydrogels of the present invention may include tougheningagents. As previously described, toughening agents are monomers whosecorresponding homo-polymers exhibit glass transition temperatures higherthan 40° C. and when added to the reactive mixture improve theelongation of the resulting silicone hydrogels. Non-limiting examples ofsuch monomers are methyl methacrylate, tert-butyl methacrylate,isobornyl methacrylate, cyclohexyl methacrylate, styrene, substitutedstyrenes, N-4-vinylbenzyl-N-alkyl acetamides, N-4-vinylbenzylpyrrolidone, and combinations thereof.

The reaction mixture may contain additional reactive or non-reactivecomponents such as but not limited to, UV absorbers, visible lightabsorbers, photochromic compounds, pharmaceuticals, nutraceuticals,antimicrobial substances, tints, pigments, copolymerizable andnon-polymerizable dyes, release agents and combinations thereof.

Classes of suitable diluents for silicone hydrogel reaction mixturesinclude alcohols having 2 to 20 carbons, amides having 10 to 20 carbonatoms derived from primary amines, and carboxylic acids having 8 to 20carbon atoms. Primary and tertiary alcohols may be used. Preferredclasses include alcohols having 5 to 20 carbons and carboxylic acidshaving 10 to 20 carbon atoms.

Specific diluents which may be used include 1-ethoxy-2-propanol,diisopropylaminoethanol, isopropanol, 3,7-dimethyl-3-octanol, 1-decanol,1-dodecanol, 1-octanol, 1-pentanol, 2-pentanol, 1-hexanol, 2-hexanol,2-octanol, 3-methyl-3-pentanol, tert-amyl alcohol, tert-butanol,2-butanol, 1-butanol, 2-methyl-2-pentanol, 2-propanol, 1-propanol,ethanol, 2-ethyl-1-butanol,(3-acetoxy-2-hydroxypropyloxy)-propylbis(trimethylsiloxy) methylsilane,1-tert-butoxy-2-propanol, 3,3-dimethyl-2-butanol, tert-butoxyethanol,2-octyl-1-dodecanol, decanoic acid, octanoic acid, dodecanoic acid,2-(diisopropylamino)ethanol mixtures thereof and the like.

Preferred diluents include 3,7-dimethyl-3-octanol, 1-dodecanol,1-decanol, 1-octanol, 1-pentanol, 1-hexanol, 2-hexanol, 2-octanol,3-methyl-3-pentanol, 2-pentanol, t-amyl alcohol, tert-butanol,2-butanol, 1-butanol, 2-methyl-2-pentanol, 2-ethyl-1-butanol, ethanol,3,3-dimethyl-2-butanol, 2-octyl-1-dodecanol, decanoic acid, octanoicacid, dodecanoic acid, mixtures thereof and the like.

More preferred diluents include 3,7-dimethyl-3-octanol, 1-dodecanol,1-decanol, 1-octanol, 1-pentanol, 1-hexanol, 2-hexanol, 2-octanol,1-dodecanol, 3-methyl-3-pentanol, 1-pentanol, 2-pentanol, t-amylalcohol, tert-butanol, 2-butanol, 1-butanol, 2-methyl-2-pentanol,2-ethyl-1-butanol, 3,3-dimethyl-2-butanol, 2-octyl-1-dodecanol, mixturesthereof and the like.

Aprotic solvents, including amide solvents, hydroxyl substituted, alkylsubstituted on amide portion, including cyclic and acyclic amides,including N-methylpyrrolidone, N-ethylpyrrolidone, N, N-dimethylpropionamide, hydroxyethylpyrrolidone, and the like.

Mixtures of diluents may be used. The diluents may be used in amounts upto about 55% by weight of the total of all components in the reactionmixture. More preferably the diluent is used in amounts less than about45% and more preferably in amounts between about 15 and about 40% byweight of the total of all components in the reaction mixture.

A polymerization initiator is preferably included in the reactionmixture used to form substrates such as contact lenses. Non-limitinginitiators include compounds such as lauryl peroxide, benzoyl peroxide,isopropyl percarbonate, azobisisobutyronitrile, and the like, thatgenerate free radicals at moderately elevated temperatures, andphotoinitiator systems such as aromatic alpha-hydroxy ketones,alkoxyoxybenzoins, acetophenones, acylphosphine oxides, bisacylphosphineoxides, and diketones with tertiary amines, mixtures thereof, and thelike.

Illustrative examples of photoinitiators are 1-hydroxycyclohexyl phenylketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one,bis(2,6-dimethoxybenzoyl)-2,4-4-trimethylpentyl phosphine oxide(DMBAPO), bis(2,4,6-trimethylbenzoyl)-phenyl phosphineoxide (Irgacure819), 2,4,6-trimethylbenzyldiphenyl phosphine oxide and2,4,6-trimethylbenzoyl diphenylphosphine oxide, benzoin methyl ester anda combination of camphorquinone and ethyl 4-(N,N-dimethylamino)benzoate.Commercially available visible light initiator systems include Irgacure819, Irgacure 1700, Irgacure 1800, Irgacure 819, Irgacure 1850 (all fromCiba Specialty Chemicals) and Lucirin TPO initiator (available fromBASF). Commercially available UV photoinitiators include Darocur 1173and Darocur 2959 (Ciba Specialty Chemicals). These and otherphotoinitiators which may be used are disclosed in Volume III,Photoinitiators for Free Radical Cationic & Anionic Photopolymerization,2nd Edition by J. V. Crivello & K. Dietliker; edited by G. Bradley; JohnWiley and Sons; New York; 1998, which is incorporated herein byreference.

The initiator is used in the reaction mixture in effective amounts toinitiate polymerization of the reaction mixture typically in amountsfrom about 0.1 to about 2 weight percent of the reactive mixture.Polymerization of the reaction mixture can be initiated using theappropriate choice of heat, visible light, ultraviolet irradiation, orother means depending on the polymerization initiator used.Alternatively, initiation can be conducted without a photoinitiatorusing e-beam, for example. However, when a photoinitiator is used, thepreferred initiators are bisacylphosphine oxides, such asbis(2,4,6-trimethylbenzoyl)-phenyl phosphine oxide (Irgacure 819®) or acombination of 1-hydroxycyclohexyl phenyl ketone andbis(2,6-dimethoxybenzoyl)-2,4-4-trimethylpentyl phosphine oxide(DMBAPO), and the preferred method is visible light irradiation. Themost preferred photoinitiator is bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Irgacure 819®).

The reaction mixtures can be formed by any of the methods known to thoseskilled in the art, such as shaking or stirring, and then used to formpolymeric articles or devices by known methods. For example, biomedicaldevices may be prepared by mixing reactive components and the diluentswith a polymerization initiator and curing by appropriate conditions toform a product that can be subsequently formed into the appropriateshape by lathing, cutting and the like. Alternatively, the reactionmixture may be placed in a mold and subsequently cured into theappropriate article.

Second Hydrogel Reactive Mixture

The second hydrogel reactive mixture used in the peripheral zone may beformed from any known conventional or silicone hydrogel formulation. Thesecond hydrogel reactive mixture, may be a silicone hydrogel reactivemixture, and may be a reactive mixture having similar components tothose described for the first silicone hydrogel reactive mixture,described above.

The second reactive mixture may comprise the components described abovefor the first silicone hydrogel reactive mixture, but without N-alkylmethacrylamide monomer.

The second reactive mixture may comprise

-   -   a. between about 1 and about 15 wt % at least one acyclic        polyimide;    -   b. at least one first mono-functional, hydroxyl substituted        poly(disubstituted siloxane) having 4 to 8 siloxane repeating        units;    -   c. at least one second hydroxyl substituted poly(disubstituted        siloxane) selected from the group consisting of mono-functional        hydroxyl substituted poly(disubstituted siloxane)s having 10 to        200 or 10-100 siloxane repeating units and multifunctional        hydroxyl substituted poly(disubstituted siloxane)s having 10 to        200, or 10 to 100 siloxane repeating units, and mixtures        thereof;    -   d. about 5 to about 30 wt % at least one additional hydrophilic        monomer;    -   e. wherein the first hydroxyl substituted, linear        poly(disubstituted siloxane) and the second mono-functional        hydroxyl substituted, linear poly(disubstituted siloxane) are        present in concentrations to provide a ratio of wt % of all        first hydroxyl substituted, linear poly(disubstituted siloxane)        to wt % of all one second hydroxyl substituted        poly(disubstituted siloxane)s of 0.4-1.3, or 0.4-1.0.

The reactive monomer mixture also includes a mixture ofhydroxyl-containing silicone components of different molecular weightsor different compositions. The first hydroxyl-containing siliconecomponent may be selected from hydroxyl-containing silicone monomers,and hydroxyl containing polydisubstituted siloxanes having at least 4polydisubstituted siloxane repeating units or 4-8 polydisubstitutedsiloxane repeating units; and at least one monovalent reactive group.When the first hydroxyl-containing silicone component is ahydroxyl-containing silicone monomer, the second hydroxyl-containingsilicone component may be selected from hydroxyl substitutedpoly(disubstituted siloxane) having 4 to 8 siloxane repeating units,monofunctional hydroxyl substituted poly(disubstituted siloxane)s having10 to 200, 10-100 or 10-20 siloxane repeating units and multifunctionalhydroxyl substituted poly(disubstituted siloxane)s having 10 to 200, or10 to 100 siloxane repeating units, and mixtures thereof. When the firsthydroxyl-containing silicone component is a hydroxyl-substitutedpoly(disubstituted siloxane) having 4 to 8 siloxane repeating units, thesecond hydroxyl-containing silicone component may be selected frommonofunctional hydroxyl substituted poly(disubstituted siloxane)s having10 to 200, 10-100 or 10-20 siloxane repeating units and multifunctionalhydroxyl substituted poly(disubstituted siloxane)s having 10 to 200, or10 to 100 siloxane repeating units, and mixtures thereof. Thehydroxyl-containing silicone components may be any of those describedabove. When present, the hydroxyl-containing silicone components may bepresent in amounts between about 40-about 70, or about 45-about 70 wt %.

The hydrophilic components (including the charged components and thehydrophilic hydroxyl components, but excluding the acyclic polyamide)may be present in the second reactive mixture in amounts up to about 50wt %, or in an amount in the range of about 10 to about 50 wt. %, or inthe range of about 10 to about 40 wt. %, based on the total weight ofthe reactive components in the reactive monomer mixture.

The second hydrogel reactive mixture may contain cross-linking agents inamounts from about 0.000415 to about 0.0156 mole per 100 grams ofreactive components in the reaction mixture.

The second hydrogel reactive mixture may comprise wetting agents,non-hydroxyl silicone-containing component, additional components anddiluents, all as described above (including the amounts describedabove).

Micro-dosing technology may be utilized to fabricate or manufacture acontact lens 100 having an optic zone 102 with a higher Young's modulusthan the surrounding lens. In a first step, a standard front curve for agiven prescription is positioned to accept the reactive mixtures forforming a contact lens. The first silicone hydrogel reactive mixture isdosed into the center portion of the contact lens front curve mold. Asecond silicone hydrogel reactive mixture is dosed on top of the firstsilicone hydrogel reactive mixture. The first silicone hydrogel reactivemixture will generally have a higher viscosity that the second siliconehydrogel reactive mixture. This allows for miscible or partiallymiscible reactive mixtures to be used for the first and second siliconehydrogel reactive mixtures. The use of miscible, or partially misciblereactive mixtures is a benefit, as it provides a transition zone wheremixing of the two reaction mixtures occurs. This provides a more gradualtransition, which may lessen interfacial stress between the peripheraland optic zones of the cured contact lens.

The contact lens mold is closed by the deposition of the base curvemold. The closed mold is then positioned so that the reactive mixturesmay be cured into a final contact lens with a central optic or opticzone having a Young's modulus as is set forth above.

Referring to FIGS. 2A and B, two methods of manufacturing contact lensesare schematically shown. In the first method shown in FIG. 2a , a frontcurve 11 a is provided at step 10 a. The front curve 11 a is one part ofthe two part mold that is concave in shape so that the depositedmaterial is held in the center of the mold by gravity. At step 12 a, asmall and precise dose of first silicone hydrogel reactive mixturemixture 13 a, or is supplied or dosed on a surface of the front curvemold 11 a preferably in a substantially central location and insubstantially circular configuration.

The first silicone hydrogel reactive mixture may be dosed in a centralcircular area within the optic zone of the contact lens. The centralcircular area may be the same size as the optic zone, which in a typicalcontact lens is about 9 mm or less in diameter. In one embodiment, thecentral circular area has a diameter of between about 4 and about 7 mmand in another between about 4 and about 6 mm in diameter.

Optionally, the first silicone hydrogel reactive mixture may be at leastpartially polymerized through a controlled curing mechanism at step 12a. Then, a dose of second silicone hydrogel reactive mixture, is dosedon the top of the first silicone hydrogel reactive mixture 13 a at step14 a. The dose of second silicone hydrogel reactive mixture 15 a fillsthe concave front curve 11 a to the desired amount and then, at step 16a, the base curve 17 a is provided and the mold halves 11 a, 17 a areput into their final curing position and the monomer mixtures are curedand/or polymerized completing the molding process. Where thepolymerization process includes a photo-polymerization mechanism, theradiation, may be directed to either the front curve mold half or thebase curve mold half, or both. The molded lens is then extracted toremove the un-desired chemical components and hydrated.

An alternative method is shown in FIG. 2b in which the first dose offirst silicone hydrogel reactive mixture 13 b is provided in the centerof a front curve mold 11 b at step 12 b and then an annular ring ofsecond silicone hydrogel reactive mixture 15 b is dosed at the edge ofthe front curve mold 11 b at step 14 b. The resultant annular ring ofsecond silicone hydrogel reactive mixture 15 b is drawn to the center ofthe front curve by gravity. The base curve mold 17 b is then suppliedand the curing is initiated and completed at step 16 b and theextraction and hydration step(s) (not shown) proceed to form the finalhydrogel contact lens product.

In order to provide a hydrogel contact lens with acceptable separationof the two regions (print quality) and low distortion, generally interms of first silicone hydrogel reactive mixture 11 distribution, ithas been found that, increasing the viscosities of the monomer mixtures13, 15 and, specifically, increasing the viscosity of the first siliconehydrogel reactive mixture 13 as compared to the second silicone hydrogelreactive mixture 15, reduces molecular diffusion of the monomers 13, 15thereby maintaining the first silicone hydrogel reactive mixture in thecentral region. Using a first silicone hydrogel reactive mixture thathas higher viscosity than the second silicone hydrogel reactive mixturehelps to reduce the shear at the interface of the two monomers mixturesthereby reducing the physical mixing. An analysis of the Stokes-Einsteinequation, shown below, illustrates the parameters that affect thediffusivity of a material:

$D = \frac{kT}{6{\pi\mu}\; r}$where D is the molecular diffusivity, k the Boltzmann constant, T thetemperature, μ the viscosity and r the radius of the molecule. Operatingat lower temperatures and using monomers of higher viscosities tends toreduce the molecular diffusion rate. In one embodiment the viscosity ofthe first silicone hydrogel reactive mixture is at least about 1000 cphigher than the viscosity of the second silicone hydrogel reactivemixture and in another embodiment at least about 1500 cp higher.

The process of the present invention may also comprise coating the lensmolds with the second silicone hydrogel material prior to dosing thefirst silicone hydrogel material. Alternatively, a third material may beapplied as a mold transfer coating. The coating may be partially orfully cured prior to dosing the first silicone hydrogel reactivemixture, or the coated molds may be heated to remove the solvent fromthe coating composition.

Existing silicone hydrogel formulations having the Young's modulus andwater contents disclosed above may be used for the second siliconehydrogel reactive mixtures. Examples of commercialized silicone hydrogelformulations includes galyficon, senofilcon, narafilcon, lotrafilcon,balafilcon, comfilcon, samfilcon, acquafilcon, stenfilcon, enfilcon,formofilcon.

The more rigid or stiffer optical zone 102 materials and the less stiffperipheral 104 lens material do not necessarily have a distincttransition, as there may be a blending of the two materials duringassembly. This would mean that the stiffness of the lens 100 may changegradually outside the optic zone, as a function of position from thecenter of the contact lens. Furthermore, the stiff optic zone 102material would be continuous from the front surface of the central opticto the back surface of the central optic of the contact lens. This isdifferent from a hybrid contact lens which encapsulates a rigid lensinsert, inside of a soft lens material shell and has a distincttransition from stiff optic zone to softer periphery. This is alsodifferent from a skirted rigid gas permeable contact lens (RGP), sincethe periphery of the contact lens is not molded onto a rigid centraloptic, but rather the two materials are molded together, creating onenon-homogenous soft contact lens.

The first and second silicone hydrogel reactive mixtures are clear,compatible with each other have the indexes of refraction within 10% ofeach other. Existing processes for forming contact lenses may be easilymodified to manufacture contact lenses in accordance with the presentinvention.

The second hydrogel reactive mixture is compatible with the partiallycured first hydrogel reactive mixture. This is a benefit in minimizingstresses between the polymers in the hybrid lens. However, because thesecond RMM is compatible with the first, prior to curing it canintercalate into the fully or partially cured first RMM. Complete mixingof the fully or partially cured RMM may undesirably change theproperties of first SH, including decreasing the modulus. According, itmay be desirable to limit the time the second RMM is in contact with thefirst partially or fully cured RMM (“dwell time”) prior to curing. Dwelltime is less than about 5 minutes and preferably is less than about 1minute. Dwell times may be decreased as temperatures increase.

Curing of the composite lenses of the present invention may be donesequentially, by fully or partially curing a center dose material, bycuring a first lens and intercalating the central material and curing,or by voxel by voxel curing using reactive components having differentreactive groups for the central and peripheral regions. Lens insertscould also be used for the central region, and any of the foregoingmethods may be combined.

Viscosity differences in optic zone and periphery monomers may be usedto maintain separation during the lens manufacturing process, such as inusing a higher viscosity central monomer that does not flow outwards tothe periphery when the lens mold is closed. Consideration must be madeto the shrinkage and expansion rates of both materials in order to forman acceptable lens.

The cure light intensity may be varied across the contact lens, tofurther vary the stiffness realized in different regions. Accordingly,by selective curing, a stiffer optic zone relative to the peripheralzone may be achieved.

Referring to FIG. 1, two methods of manufacturing composite photochromiccontact lenses are schematically shown. In the first method shown inFIG. 1a , a front curve 11 a is provided at step 10 a. The front curve11 a is one part of the two part mold that is concave in shape so thatthe deposited material is held in the center of the mold by gravity. Atstep 12 a, a small and precise dose of a first monomer mixture 13 a,comprising the N-alkyl methacrylamide, is supplied or dosed on a surfaceof the front curve mold 11 a preferably in a substantially centrallocation and in substantially circular configuration.

The central circular area may be the same size as the optic zone, whichin a typical contact lens is about 9 mm or less in diameter. In oneembodiment, the central circular area has a diameter of between about 4and about 7 mm and in another between about 4 and about 6 mm indiameter.

Optionally, the first monomer mixture may be at least partiallypolymerized through a controlled curing mechanism at step 12 a. Then, adose of a second monomer mixture, which will form a hydrogel having amodulus of less than about 200 psi, or less than about 150 psi, 15 a isdosed on the top of the first monomer mixture 13 a at step 14 a. Thedose of the second monomer mixture 15 a fills the concave front curve 11a to the desired amount and then, at step 16 a, the base curve 17 a isprovided and the mold halves 11 a, 17 a are put into their final curingposition and the monomer mixtures are cured and/or polymerizedcompleting the molding process. Where the polymerization processincludes a photo-polymerization mechanism, the radiation, may bedirected to either the front curve mold half or the base curve moldhalf, or both. The molded lens is then extracted to remove theun-desired chemical components and hydrated.

An alternative method is shown in FIG. 1b in which the first monomermixture 13 b is provided in the center of a front curve mold 11 b atstep 12 b and then an annular ring of the second monomer mixture 15 b isdosed at the edge of the front curve mold 11 b at step 14 b. Theresultant annular ring of the second reactive mixture 15 b is drawn tothe center of the front curve by gravity. The base curve mold 17 b isthen supplied and the curing is initiated and completed at step 16 b andthe extraction and hydration step(s) (not shown) proceed to form thefinal hydrogel contact lens product.

It is desirable to prevent substantial mixing of the first and secondmonomer mixtures to preserve the desired moduli values in the centraland peripheral zones. Increasing the viscosity of the first monomermixture 13 as compared to the second, peripheral monomer mixture 15, canreduce molecular diffusion of the monomers 13, 15 when a cure (eitherpartial or full) of the first monomer mixture in the central zone is notutilized. Using a first monomer mixture that has higher viscosity thanthe clear monomer mixture helps to reduce the shear at the interface ofthe two monomers mixtures thereby reducing the physical mixing. Ananalysis of the Stokes-Einstein equation, shown below, illustrates theparameters that affect the diffusivity of a material:

$D = \frac{kT}{6{\pi\mu}\; r}$where D is the molecular diffusivity, k the Boltzmann constant, T thetemperature, μ the viscosity and r the radius of the molecule. Operatingat lower temperatures and using monomers of higher viscosities tends toreduce the molecular diffusion rate. In one embodiment the viscosity ofthe first monomer mixture is at least about 1000 cp higher than theviscosity of the peripheral monomer mixture and in another embodiment atleast about 1500 cp higher.

However, controlling the viscosity of the monomer mixtures as disclosedin US2003/0142267 was insufficient to provide hydrogel contact lenseshaving suitable optics and comfort. It has been found that employing apartial or complete cure of the first monomer mixture and balancing theexpansion factor of the polymers formed from the first and secondmonomer mixture hydrogel contact lenses having desirable optics andcomfort may be produced. In one embodiment the expansion factors of thepolymers formed from the respective monomer mixtures are within about10% in some embodiments within about 8% and in other embodiments withinabout 5%. The expansion factor may be adjusted by manipulating a numberof formulation variables including the diluent concentration, theconcentration and hydrophilicity or hydrophobicity of hydrophilic andhydrophobic components and concentration of initiator and crosslinker,and combinations thereof. It may be desirable to maintain theconcentration of the silicone components and replace a part of one ofhydrophilic components. In these embodiments, multiple adjustments maybe needed to achieve the desired expansion factor.

In addition, other formulation variables may be modified to achieve thedesired expansion factor. For example, varying the concentration of thehydrophilic components, the diluent concentration and the initiatorconcentration, and combinations thereof have been effective at providingphotochromic contact lenses having desirable optics and comfort. In oneembodiment a hydrophilic polymer, such as poly(vinyl pyrrolidone) (PVP),methacrylic acid, polydimethylacrylamide or poly(vinyl methacetamide)may be added to the monomer mixtures.

The same or similar components may be used in both the first and secondmonomer mixtures. For example, it may be desirable to include the samehydrophilic components in both monomer mixtures. In this case,formulation variables in addition to the concentration of hydrophiliccomponents may be varied.

When a single sided cure is used the expansion factor may be matchedusing monomers, diluent concentration and combinations thereof. Wherecure is effected from only one side (such as during photocuring),increasing the initiator concentration may also be desirable.

In addition to using the bi-material contact lens with differences inYoung's modulus in the center and periphery, pre-tensioning of the lensmay also create additional resistance to deformation when placed on-eye.A pre-tensioned lens will require more force to deform as the internaltension must be overcome along with the elastic force from the modulus,lens shape, and lens thickness. Methods of manufacturing pre-tensionedlenses include varying the reaction rate, such as by introducingdifferent levels of oxygen or another reaction inhibitor, to the frontand back surfaces of the lens molds. The result is a lens that, intactmaintains a “dome” shape, but if cross-sectioned will tend to curl orflatten. In addition to exposing the entire front and back mold surfacesto different oxygen levels, the concentration of oxygen or anotherinhibitor may be varied across both front and back surfaces, creating acustom tension or stress profile through the lens.

The basic premise behind this pre-tensioning process is that differentplastic mold materials absorb oxygen or other reaction inhibitors atdifferent rates and retain the oxygen or other reaction inhibitors withdifferent affinities. By utilizing different materials to form the frontand back curve molds or selectively exposing the front and/or back curvemolds to oxygen or other reaction inhibitors, the reaction rate may bechanged thereby inducing stresses in the contact lens. For example,polypropylene readily absorbs oxygen while zeonor and polystyrene absorbsignificantly less. Accordingly, by utilizing polystyrene for the frontcurve mold and polypropylene for the back curve mold, with equal accessto oxygen, the back curve mold will absorb more oxygen than the frontcurve mold and thus the monomer in contact with this surface will havedifferent properties, creating a differential stress between the frontand back surfaces of the contact lens. The concentration of the oxygenor other reaction inhibitors may be further manipulated by controllingat least one of, all of, or any combination of time, temperature,concentration and pressure of the medium (environment) surrounding thefront and back curve mold surfaces. In addition, concentration ofabsorbed oxygen or other reaction inhibitors may be varied across thesurface, such as by masking the part prior to exposure or selectivelyremoving absorbed gases.

Providing that the corneal astigmatism is effectively reduced per thisdesign with a rotationally symmetric optic due to the increasedstiffness of the soft contact lens by means of the increased Young'smodulus in the central optic or optic zone or by any other suitablemeans such as varying cure light intensity and pre-tensioning of thecontact lens as described in detail herein, the contact lens would notrequire any specific on eye orientation and therefore less or nomechanical stabilization for the contact lens. If corneal astigmatismand/or high order aberrations are reduced, but not made negligible,mechanical stabilization may still be required, but variations in lensposition will have a smaller impact on visual quality. As set forthabove, an advantage of the present invention is that the stabilizationfeatures may be reduced in size or substantially eliminated, therebyproviding a more comfortable contact lens. The present invention offersa simple and elegant solution for the correction of astigmatism.

Test Methods

Standard deviations are shown in parentheses. It will be appreciatedthat all of the tests specified herein have a certain amount of inherenterror. Accordingly, the results reported herein are not to be taken asabsolute numbers, but numerical ranges based upon the precision of theparticular test. The water content was measured as follows: lenses to betested were allowed to sit in packing solution for 24 hours. Each ofthree test lens were removed from packing solution using a sponge tippedswab and placed on blotting wipes which have been dampened with packingsolution. Both sides of the lens were contacted with the wipe. Usingtweezers, the test lens were placed in a weighing pan (that waspreweighed) and the weight of the wet lenses was obtained. Two more setsof samples were prepared and weighed as above.

The dry weight was measured by placing the sample pans in a vacuum ovenwhich has been preheated to 60° C. for 30 minutes. Vacuum was applieduntil at least 0.4 inches Hg is attained. The vacuum valve and pump wereturned off and the lenses were dried for a minimum of twelve hours. Thepurge valve was opened and the oven was allowed reach atmosphericpressure. The pans were removed and weighed. The water content wascalculated as follows:

Wet  weight = combined  wet  weight  of  pan  and  lenses − weight  of  weighing  panDry  weight = combined  dry  weight  of  pan  and  lens − weight  of  weighing  pan$\mspace{79mu}{{\%\mspace{14mu}{water}\mspace{14mu}{content}} = {\frac{\left( {{{wet}\mspace{14mu}{weight}} - {{dry}\mspace{14mu}{weight}}} \right)}{{wet}\mspace{14mu}{weight}} \times 100}}$The average and standard deviation of the water content are calculatedfor the samples are reported.

Haze was measured by placing a hydrated test lens in borate bufferedsaline in a clear glass cell at ambient temperature above a flat blackbackground, illuminating from below with a fiber optic lamp(Dolan-Jenner PL-900 fiber optic light with 0.5″ diameter light guide)at an angle 66° normal to the lens cell, and capturing an image of thelens from above, normal to the lens cell with a video camera (DVC1300C:19130 RGB camera or equivalent equipped with a suitable zoomcamera lens) placed 14 mm above the lens holder. The background scatteris subtracted from the scatter of the test lens by subtracting an imageof a blank cell with borate buffered saline (baseline) using EPIX XCAP V3.8 software. The value for high end scatter (frosted glass) is obtainedby adjusting the light intensity to be between 900 to 910 meangrayscale. The value of the background scatter (BS) is measured using asaline filled glass cell. The subtracted scattered light image isquantitatively analyzed, by integrating over the central 10 mm of thelens, a frosted glass standard as a high-end scattering standard. Thelight intensity/power setting was adjusted to achieve a mean grayscalevalue in the range of 900-910 for the frosted glass standard; at thissetting, the baseline mean grayscale value was in the range of 50-70.The mean grayscale values of the baseline and frosted glass standard arerecorded and used to create a scale from zero to 100, respectively.Then, the mean grayscale values and standard deviations were measuredfor the test lenses and compared a frosted glass standard. The lightintensity/power setting was adjusted to achieve a mean grayscale valuein the range of 900-910 for the frosted glass standard; at this setting,the baseline mean grayscale value was in the range of 50-70. The meangrayscale values of the baseline and frosted glass standard are recordedand used to create a scale from zero to 100, respectively. In thegrayscale analysis, the mean and standard deviations of the baseline,frosted glass, and every test lens was recorded. For each lens, a scaledvalue was calculated according to the equation: scaled value equals themean grayscale value (lens minus baseline) divided by the mean grayscalevalue (frosted glass minus baseline) times by 100. Three to five testlenses are analyzed, and the results are averaged.

Water content was measured gravimetrically. Lenses were equilibrated inpacking solution for 24 hours. Each of three test lens are removed frompacking solution using a sponge tipped swab and placed on blotting wipeswhich have been dampened with packing solution. Both sides of the lensare contacted with the wipe. Using tweezers, the test lens are placed ina tared weighing pan and weighed. The two more sets of samples areprepared and weighed. All weight measurements were done in triplicate,and the average of those values used in the calculations. The wet weightis defined as the combined weight of the pan and wet lenses minus theweight of the weighing pan alone.

The dry weight was measured by placing the sample pans in a vacuum ovenwhich has been preheated to 60° C. for 30 minutes. Vacuum was applieduntil the pressure reaches at least 1 inch of Hg is attained; lowerpressures are allowed. The vacuum valve and pump are turned off and thelenses are dried for at least 12 hours; typically overnight. The purgevalve is opened allowing dry air or dry nitrogen gas to enter. The ovenis allowed reach atmospheric pressure. The pans are removed and weighed.The dry weight is defined as the combined weight of the pan and drylenses minus the weight of the weighing pan alone. The water content ofthe test lens was calculated as follows:

${\%\mspace{14mu}{water}\mspace{14mu}{content}} = {\frac{\left( {{{wet}\mspace{14mu}{weight}} - {{dry}\mspace{14mu}{weight}}} \right)}{{wet}\mspace{14mu}{weight}} \times 100}$The average and standard deviation of the water content were calculatedand the average value reported as the percent water content of the testlens.

The refractive index (RI) of a contact lens was measured by a LeicaARIAS 500 Abbe refractometer in manual mode or by a Reichert ARIAS 500Abbe refractometer in automatic mode with a prism gap distance of 100microns. The instrument was calibrated using deionized water at 20° C.(+/−0.2° C.). The prism assembly was opened and the test lens placed onthe lower prism between the magnetic dots closest to the light source.If the prism is dry, a few drops of saline were applied to the bottomprism. The front curve of the lens was against the bottom prism. Theprism assembly was then closed. After adjusting the controls so that theshadow line appeared in the reticle field, the refractive index wasmeasured. The RI measurement was made on five test lenses. The averageRI calculated from the five measurements was recorded as the refractiveindex as well as its standard deviation.

Oxygen permeability (Dk) was determined by the polarographic methodgenerally described in ISO 9913-1:1996 and ISO 18369-4:2006, but withthe following modifications. The measurement was conducted at anenvironment containing 2.1% oxygen created by equipping the test chamberwith nitrogen and air inputs set at the appropriate ratio, for example,1800 mL/min of nitrogen and 200 mL/min of air. The t/Dk is calculatedusing the adjusted oxygen concentration. Borate buffered saline wasused. The dark current was measured by using a pure humidified nitrogenenvironment instead of applying MMA lenses. The lenses were not blottedbefore measuring. Four lenses were stacked instead of using lenses ofvarious thickness (t) measured in centimeters. A curved sensor was usedin place of a flat sensor; radius was 7.8 mm. The calculations for a 7.8mm radius sensor and 10% (v/v) air flow are as follows:Dk/t=(measured current−dark current)×(2.97×10⁻⁸ mL O₂/(μA-sec-cm²-mm Hg)The edge correction was related to the Dk of the material.For all Dk values less than 90 barrers:t/Dk(edge corrected)=[1+(5.88×t)]×(t/Dk)

For Dk values between 90 and 300 barrers:t/Dk(edge corrected)=[1+(3.56×t)]×(t/Dk)

For Dk values greater than 300 barrers:t/Dk(edge corrected)=[1+(3.16×t)]×(t/Dk)Non-edge corrected Dk was calculated from the reciprocal of the slopeobtained from the linear regression analysis of the data wherein the xvariable was the center thickness in centimeters and the y variable wasthe t/Dk value. On the other hand, edge corrected Dk was calculated fromthe reciprocal of the slope obtained from the linear regression analysisof the data wherein the x variable was the center thickness incentimeters and the y variable was the edge corrected t/Dk value. Theresulting Dk value was reported in barrers.

Wettability of lenses was determined using the methods below. Dynamiccontact angle (DCA) was determined by a Wilhelmy plate method using aCahn DCA-315 instrument at room temperature and using deionized water asthe probe solution. The experiment was performed by dipping the lensspecimen of known parameter into the packing solution of known surfacetension while measuring the force exerted on the sample due to wettingby a sensitive balance. The advancing contact angle of the packingsolution on the lens is determined from the force data collected duringsample dipping. The receding contact angle is likewise determined fromforce data while withdrawing the sample from the liquid. The Wilhelmyplate method is based on the following formula: Fg=

cos

, wherein F=the wetting force between the liquid and the lens (mg),g=gravitational acceleration (980.665 cm/sec²),

=surface tension of probe liquid (dyne/cm),

=the perimeter of the contact lens at the liquid/lens meniscus (cm),

=the dynamic contact angle (degree), and B=buoyancy (mg). B is zero atthe zero depth of immersion. Four test strips were cut from the centralarea of the contact lens. Each strip was approximately 5 mm in width andequilibrated in packing solution. Then, each sample was cycled fourtimes, and the results were averaged to obtain the advancing andreceding contact angles of the lens.

Wettability of lenses was also determined using a sessile drop techniquemeasured using KRUSS DSA-100 TM instrument at room temperature and usingDI water as probe solution. The lenses to be tested (3-5/sample) wererinsed in DI water to remove carry over from packing solution. Each testlens was placed on blotting lint free wipes which were dampened withpacking solution. Both sides of the lens were contacted with the wipe toremove surface water without drying the lens. To ensure properflattening, lenses were placed “bowl side down” on the convex surface ofcontact lens plastic molds. The plastic mold and the lens were placed inthe sessile drop instrument holder, ensuring proper central syringealignment. A 3 to 4 microliter drop of deionized water was formed on thesyringe tip using DSA 100-Drop Shape Analysis software ensuring theliquid drop was hanging away from the lens. The drop was releasedsmoothly on the lens surface by moving the needle down. The needle waswithdrawn away immediately after dispensing the drop. The liquid dropwas allowed to equilibrate on the lens for 5 to 10 seconds, and thecontact angle was measured between the drop image and the lens surface.

The mechanical properties of the contact lenses were measured by using atensile testing machine such as an Instron model 1122 or 5542 equippedwith a load cell and pneumatic grip controls. Minus one diopter lens isthe preferred lens geometry because of its central uniform thicknessprofile. A dog-bone shaped sample cut from a −1.00 power lens having a0.522 inch length, 0.276 inch “ear” width and 0.213 inch “neck” widthwas loaded into the grips and elongated at a constant rate of strain of2 inches per minute until it breaks. The center thickness of thedog-bone sample was measured using an electronic thickness gauge priorto testing. The initial gauge length of the sample (Lo) and samplelength at break (Lf) were measured. At least five specimens of eachcomposition were measured, and the average values were used to calculatethe percent elongation to break: percent elongation=[(Lf−Lo)/Lo]×100.The tensile modulus was calculated as the slope of the initial linearportion of the stress-strain curve; the units of modulus are pounds persquare inch or psi. The tensile strength was calculated from the peakload and the original cross-sectional area: tensile strength=peak loaddivided by the original cross-sectional area; the units of tensilestrength are psi. Toughness was calculated from the energy to break andthe original volume of the sample: toughness=energy to break divided bythe original sample volume; the units of toughness are in-lbs/in³.

Samples cast as flats were also measured by Instron testing; however,the test articles were prepared from flat circular plastic molds(diameter about 15 mm) similar to the molds used to make contact lensesbut without curvature to produce flat round disks. The molds weredesigned to make disks with center thicknesses between 250 and 550microns, depending on the volume of reactive monomer mixture dosed. Thedisks were cut to the desired sample size (width: 3.1 mm; length: about7 mm). The crosshead of a constant rate-of-movement type-testing machinewas equipped with a 100 Newton load cell and pneumatic action grips (250Newton maximum) with diamond serrated jaw faces. The specimen was loadedinto the grips and then elongated at 1 inch per minute until it breaks.The tensile properties are obtained from the resulting stress-straincurve. Additionally, for all mechanical testing experiments, sampleswere stored in packing solution until immediately before the analysis tominimize the effects of dehydration.

Center thickness; was individually measured using an electronicthickness gauge.

The following abbreviations will be used throughout the Examples

BC: back curve plastic mold

FC: front curve plastic mold

NVP: N-vinylpyrrolidone (Acros Chemical)

DMA: N,N-dimethylacrylamide (Jarchem)

HEMA: 2-hydroxyethyl methacrylate (Bimax)

NMMA: N-methyl methacrylamide

VMA: N-vinyl N-methyl acetamide (Aldrich)

Blue HEMA:1-amino-4-[3-(4-(2-methacryloyloxy-ethoxy)-6-chlorotriazin-2-ylamino)-4-sulfophenylamino]anthraquinone-2-sulfonicacid, as described in Example 4 of U.S. Pat. No. 5,944,853

Styryl-TRIS: tris(trimethylsiloxy)silyl styrene

pVMA: poly(N-vinyl N-methyl acetamide)

PVP: poly(N-vinylpyrrolidone) K90 (ISP Ashland)

EGDMA: ethylene glycol dimethacrylate (Esstech)

TEGDMA: triethylene glycol dimethacrylate (Esstech)

TMPTMA: trimethylolpropane trimethacrylate (Esstech)

BMPP: 2,2-bis(4-methacryloxyphenyl)-propane (PolySciences)

BAPP: 2,2-bis[4-(2-acryloxyethoxy)phenyl]propane (PolySciences)

BHMPP: 2,2-bis[4-(2-hydroxy-3-methacryloxypropoxy)phenyl]propane(PolySciences)

Tegomer V-Si 2250: diacryloxypolydimethylsiloxane, having 20 averagedimethylsiloxy repeating units (Evonik)

D3O: 3,7-dimethyl-3-octanol (Vigon)

Irgacure 819: bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide

Irgacure 1870: blend ofbis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphineoxide and1-hydroxy-cyclohexyl-phenyl-ketone

mPDMS: monomethacryloxypropyl terminated mono-n-butyl terminatedpolydimethylsiloxane, (800-1000 MW) (Gelest)

HO-mPDMS: mono-(2-hydroxy-3-methacryloxypropyl)-propyl ether terminatedmono-n-butyl terminated polydimethylsiloxane (400-1000 MW) (DSM)

SiMAA:2-methyl-2-hydroxy-3-[3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]disiloxanyl]propoxy]propylester (Toray)

SA2:N-(2,3-dihydroxylpropyl)N-(3-tetra(dimethylsiloxy)dimethylbutylsilane)propyl)acrylamide

TAM: t-amyl alcohol (BASF)

3E3P: 3-ethyl 3-pentanol

DI water: deionized water

IPA: isopropyl alcohol

Norbloc: 2-(2″-hydroxy-5-methacrylyloxyethylphenyl)-2H-benzotriazole(Janssen)

PP: polypropylene

Zeonor: polycycloolefin thermoplastic polymer (Nippon Zeon Co Ltd)

Borate Buffer: a solution prepared by dissolving 8.3 gm NaCl (from SigmaAldrich), 9.1 gm boric acid (from Mallinckrodt) and 1 gm sodium borate(from Mallinckrodt) in 1 L deionized water (from Milli Q).

EXAMPLES Examples 1-10

Each reactive mixture was formed by mixing the reactive componentslisted in Table 1, filtering through a 3 μm filter using a heated orunheated stainless steel or glass syringe, and then degassed by applyingvacuum at ambient temperature for about 15 minutes. In a glove box witha nitrogen gas atmosphere and less than 0.1 percent oxygen gas, 75-100μL of the reactive mixture was then dosed at room temperature into theFC. The BC was then placed on the front curve mold. The molds wereequilibrated for a minimum of twelve hours in the glove box prior todosing. The tray was transferred into an adjacent glove box maintainedat 60-65° C., and the lenses were cured from the top for 20 minutesusing TLO3 fluorescent bulbs having intensity of 4-5 mW/cm². The lightsource was about six inches above the trays. A detailed description ofthe curing process and apparatus can be found in U.S. Pat. No.8,937,110.

The lenses were manually de-molded with most lenses adhering to the FCand released by suspending the 64 lenses in about one liter of aqueousIPA solution for about one or two hours, followed by washing withanother aqueous IPA solution, two times with DI, and finally two timeswith borate buffered packaging solution. The concentrations of theaqueous IPA solutions are listed in Table 1. Each washing step lastedabout 30 minutes. The lenses were sterilized by autoclaving at 122° C.for 30 minutes. The physical and mechanical properties of the sterilelenses were measured and are listed in Table 2.

TABLE 1 Component Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Ex 6 Ex 7 Ex 8 Ex 9 Ex 10 OH-43.2 43 42.75 42.5 43.5 41.5 41.5 41.5 43.5 43.5 mPDMS n = 4 NMMA 15 1515 15 15 15 15 15 15 15 HEMA 16.98 16.98 16.98 16.98 16.98 16.98 14.4812 13.98 13.98 pVMA 10 10 10 10 7 7 7 7 10 10 (507 KDa) Tegomer 10.710.5 10.25 10 10 10 10 10 10 10 2250 EGDMA 2.1 2.5 3 3.5 5.5 7.5 7.5 7.55.5 7.5 Norbloc 1.75 1.75 1.75 1.75 1.75 1.75 1.75 1.75 1.75 1.75 TMPTMA0 0 0 0 0 0 2.5 4.98 0 0 CGI 819 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.250.25 0.25 Blue HEMA 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02Diluent 23 23 23 23 23 23 23 23 23 23 D3O 100 100 100 100 100 100 100100 100 100 FC Z Z Z Z 9:1 Z:TT 9:1 Z:TT 9:1 Z:TT 9:1 Z:TT 9:1 Z:TT 9:1Z:TT BC Z Z Z Z PP PP PP PP PP PP % IPA 40 40 40 40 40 40 40 40 40 40release % IPA wash 70 70 70 70 50 50 50 50 50 50

TABLE 2 Mechanicals % % DCA CT Modulus TS Tough- Elong Ex# Water Haze(°) D_(k) (μm) (psi) (psi) ness (%) RI 1 28.6 7 34 96 121 1727 469 23680 1.4435 2 27.8 8 32 102 125 1907 498 238 76 1.4459 Ex. 2 NM NM NM NMNM 2287 NM NM NM NM flats Ex. 3 27 4 44 93 122 2145 476 152 55 1.4467Ex. 3 NM NM NM NM 332 5038 279 14 11 NM Flats 4 26.5 5 39 85 133 2415441 103 46 1.4467 5 18.6 2 41 83 NM NM NM NM NM 1.454 6 17.5 4 39 96 1873030 250 14 262 1.4605 Ex. 6 NM NM NM NM NM 7794 NM NM NM NM Flats 714.3 4 28 58 NM NM NM NM NM NM 8 12.9 3 29 50 298 17399 292 2 5 1.468 921.2 4 55 111 555 4251 88 0.7 7.1 NM 10  19.2 4 41 93 547 6588 141 6.31.4 NMFormulations of the present invention provide a wide range of moduli. Byvarying the concentration and type of crosslinker (such as including ashort chain, higher functionality crosslinker, such as TMTPA), moduli upto about 20,000 psi can be achieved.

Examples 11-22

Each reactive mixture was formed by mixing the reactive componentslisted in Tables 3 and 4 and then degassed by applying vacuum at ambienttemperature for about 20 minutes. In a glove box with a nitrogen gasatmosphere and less than 0.1 percent oxygen gas, about 100 μL of thereactive mixture was then dosed at room temperature into the FC madefrom made from the materials shown in Tables 3 and 4. The BC made fromthe materials shown in Tables 3 and 4 was then placed on the front curvemold. A quartz plate was placed on top of a tray of eight such moldassemblies to maintain proper fitting. The molds were equilibrated for aminimum of twelve hours in the glove box prior to dosing. The tray wastransferred into an adjacent glove box maintained at 60-65° C., and thelenses were cured for 12 minutes from the top using TLO3 fluorescentbulbs having intensity of 4-5 mW/cm².

The lenses were manually de-molded with most lenses adhering to the BCand released using 40% IPA, followed by washing two times with 40% IPAfor about 0.5 to 1 hour except as noted in the tables, two times with DIwater for about 0.5 to 1 hour, and finally two times with boratebuffered packaging solution for about 30 minutes. The lenses weresterilized by autoclaving at 122° C. for 30 minutes. The physical andmechanical properties of the sterile lenses were measured and are listedin Table 5.

TABLE 3 Component Ex11 Ex12 Ex13 Ex14 Ex15 Ex16 Ex17 Ex18 SiMAA 42.821.4 21.4 0 0 0 0 0 Styryl TRIS 0 0 21.4 42.8 42.8 42.8 42.8 42.8 TRIS 021.4 0 0 0 0 0 0 NMMA 15 15 15 15 15 15 15 18 HEMA 16.98 16.98 16.98 1716.98 16.89 16.98 16.98 pVMA (507 KDa) 10 10 10 0 0 0 7 7 pVMA (617 KDa)0 0 0 10 10 0 0 0 pVMA (700 KDa) 0 0 0 0 0 10 0 0 Tegomer 2250 10.2 10.210.2 10.2 10.2 10.2 13.2 10.2 EGDMA 3 3 3 3 3 3 3 3 Norbloc 1.75 1.751.75 1.75 1.75 1.75 1.75 1.75 TMPTMA 0 0 0 0 0 0 2.5 4.98 CGI 819 0.250.25 0.25 0.25 0 0 0.25 0.25 CGI 1870 0 0 0 0 0.34 0.34 0 0 Blue HEMA0.02 0.02 0.02 0 0.02 0.02 0.02 0.02 FC 9:1 9:1 9:1 9:1 Z 9:1 9:1 9:1Z:TT Z:TT Z:TT Z:TT Z:TT Z:TT Z:TT BC PP PP PP PP 55:45 PP PP PP  Z:PP %IPA Wash 40 40 40 40 40 40 None None Diluent 23 23 23 23 23 23 23 23 D30100 100 100 100 100 100 100 100

TABLE 4 Component Ex 19 Ex 20 Ex 21 Ex 22 SiMAA 21.4 0 0 0 Styryl TRIS21.4 42.8 42.8 42.8 NMMA 15 15 12.5 10.5 HEMA 16.98 16.98 16.98 16.98DMA 0 0 2 4 pVMA (507 KDa) 0 0 10 10 PVP K90 10 10 0 0 Tegomer 2250 10.210.2 10.2 10.2 EGDMA 3 3 3.5 3.5 Norbloc 1.75 1.75 1.75 1.75 CGI 8190.25 0.25 0.25 0.25 Blue HEMA 0.02 0.02 0.02 0.02 FC Material 9:1 9:19:1 9:1 Z:TT Z:TT Z:TT Z:TT BC Material PP PP PP PP % IPA Wash 40 40 4040 Diluent 23 23 23 23 D3O 100 100 100 100

TABLE 5 Mechanicals Ex- Mod- ample % % DCA CT ulus TS Tough- Elong. #Water Haze (degree) D_(k) (μm) (psi) (psi) ness (%) RI Ex 11 24.9 4.960.6 NM NM NM NM NM NM NM Ex 12 24 7 55.8 NM NM NM NM NM NM NM Ex 1322.6 15.8 38.4 NM 399 32562 NM NM 9.2 NM Ex 14 21.5 26 37 NM 405 411812147 106 10.7 1.467 Ex 15 20 19 56.4 199 370 57251 2469 156 12 NM Ex 1625 141 34 NM 186 37983 1445 47 10 1.4464 Ex 17 16.2 55 42.9 83 NM NM NMNM NM NM Ex 18 17.7 63 36.4 NM NM NM NM NM NM NM Ex 19 20.8 13 38 NM 29732267 1331 60.2 8.5 1.464 Ex 19 NM NM NM NM 288 32267 1331 60.2 8.5 NMflats Ex 20 17.1 44 32.7 NM 276 61629 2521 98.6 8.5 1.472 Ex. 20 NM NMNM NM 292 53600 1989 56.3 8.5 NM flats Ex 21 20.3 20 35.3 NM 290 563332339 90.7 9 1.467 Ex. 21 NM NM NM NM 299 46901 1956 61.2 8.9 NM flats Ex22 18.3 20 39 NM 286 53690 2145 79.1 8.8 1.467 Ex. 22 NM NM NM NM 28942899 1589 40.8 8.6 NM flats

Silicone hydrogels having moduli in excess of 60,000 psi but stilldisplaying water contents of 15 to about 25% were produced. The siliconehydrogels displayed desirable haze, Dk and contact angles.

Examples 23-32

Each reactive mixture was formed by mixing the reactive componentslisted in Table 6 and then degassed by applying vacuum at ambienttemperature for about 20 minutes. In a glove box with a nitrogen gasatmosphere and less than 0.1 percent oxygen gas, about 100 μL of thereactive mixture was then dosed at room temperature into the FC madefrom Zeonor. The BC made from 55:45 (w/w) blend of Zeonor:polypropylenewas then placed on the front curve mold. The molds were equilibrated fora minimum of twelve hours in the glove box prior to dosing. The tray wastransferred into an adjacent glove box maintained at 60-65° C., and thelenses were cured from the top for 20 minutes using 420 nm LED lightshaving intensity of 4-5 mW/cm².

The lenses were manually de-molded with most lenses adhering to the BCand released using 40% IPA overnight, followed by washing with 40% IPA0.5 to 1 hour, two times with DI water for about 0.5 to 1 hour, andfinally two times with borate buffered packaging solution for about 30minutes. The lenses were sterilized by autoclaving at 122° C. for 30minutes. The physical and mechanical properties of the sterile lenseswere measured and are listed in Table 7.

TABLE 6 Component Ex 23 Ex 24 Ex 25 Ex 26 Ex 27 Ex 28 Ex 29 Ex 30 Ex 31Ex 32 Styryl TRIS 42.8 42.8 42.8 42.8 42.8 42.8 42.8 42.8 42.8 42.8 NMMA15 15 15 12 9 15 15 15 15 15 HEMA 16.64 13.64 10.64 10.64 16.64 10.6410.64 10.64 10.64 10.64 DMA 3 6 9 12 9 9 9 9 9 9 PVP K90 7 7 7 7 7 7 7 77 7 Tegomer 2250 10.2 10.2 10.2 10.2 10.2 10.2 10.2 10.2 10.2 10.2 EGDMA3 3 3 3 3 3 3 3 3 3 Norbloc 2 2 2 2 2 2 2 2 2 2 CGI 1870 0.34 0.34 0.340.34 0.34 0.34 0.34 0.34 0.34 0.34 Blue HEMA 0.02 0.02 0.02 0 0.02 0.020.02 0.02 0.02 0.02 Diluent 23 23 23 23 23 20 25 30 35 40 D3O 100 100100 100 100 100 100 100 100 100

TABLE 7 Mechanicals Sessile Mod- % % Drop CT ulus TS Tough- Elong. Ex #Water Haze (°) Dk (μm) (psi) (psi) ness (%) RI Ex 23 16 71 44.9 83 18760219 2212 63.5 9.1 1.4713 Ex 24 17 83 64.4 93 177 58448 2173 61 9.61.4722 Ex 25 23 90 46.6 NM 184 58232 1996 61 9.6 1.4720 Ex 26 22 94 60.996 169 40827 1454 39.8 10 1.4685 Ex 27 19 64 50.4 109 188 43687 191963.3 10.2 1.4701 Ex 28 20 10 25.7 NM 207 27958 1087 37.8 9.8 1.4591 Ex29 20 14 25.2 NM 212 27514 1067 35.8 9.9 1.4609 Ex 30 19 45 30.5 NM 21525849 1004 31.7 9.1 1.4568 Ex 31 21 52 29.8 NM 177 27993 1102 39.4 9.71.4512 Ex 32 19 18 31.6 NM 170 30335 1064 34.7 12.3 1.4532

Each reactive mixture was formed by mixing the reactive componentslisted in Table 8 and then degassed by applying vacuum at ambienttemperature for about 20 minutes. In a glove box with a nitrogen gasatmosphere and less than 0.1 percent oxygen gas, about 100 μL of thereactive mixture was then dosed at room temperature into the FC madefrom Zeonor. The BC made from 55:45 (w/w) blend of Zeonor:polypropylenewas then placed on the front curve mold. A quartz plate was placed ontop of a tray of eight such mold assemblies to maintain proper fitting.The molds were equilibrated for a minimum of twelve hours in the glovebox prior to dosing. The tray was transferred into an adjacent glove boxmaintained at 60-65° C., and the lenses were cured from the bottom for20 minutes using TL03 lights having intensity of 4-5 mW/cm².

The lenses were manually de-molded with most lenses adhering to the BCand released using 40% IPA overnight, and 50% IPA overnight, followed bywashing two times with 40% IPA for about 0.5 to 1 hour, two times withDI water for about 0.5 to 1 hour, and finally two times with boratebuffered packaging solution for about 30 minutes, and finally two timeswith borate buffered packaging solution for about 30 minutes. The lenseswere sterilized by autoclaving at 122° C. for 30 minutes. The physicaland mechanical properties of the sterile lenses of Examples 33-36 weremeasured and are listed in Table 9.

TABLE 8 Component Ex 33 Ex 34 Ex 35 Ex 36 Ex 37 Styryl TRIS 42.8 44.844.3 43.8 42.8 NMMA 15 15 15 15 15 HEMA 17 16.98 16.98 16.98 16.98 pVMA(507 KDa) 10 10 10 10 10 Tegomer 2250 10.2 10.2 10.2 10.2 10.2 EGDMA 3 11.5 2 3 Norbloc 1.75 1.75 1.75 1.75 1.75 CGI 819 0.25 0.25 0.25 0.250.25 Blue HEMA 0 0.02 0.02 0.02 0.02 Diluent 23 30 30 30 30 3E3P 100 100100 100 100

TABLE 9 Mechanicals Mod- % % Sessile CT ulus TS Tough- Elong. Ex # WaterHaze Drop (°) (μm) (psi) (psi) ness (%) Ex 33 29 370 41.6 446 30106 124957.1 10.8 Ex 34 29 230 38 452 32991 1517 53.8 10.5 Ex 35 26 101 34.7 46130656 1333 40.3 8.6 Ex 36 21 43 34.8 400 42900 1978 83.9 10.1

The silicone hydrogels of Examples 33-36 display moduli up to 43,000psi, and water contents between about 20 and 30%.

Examples 38-53

Each reactive mixture was formed by mixing the reactive componentslisted in Tables 10 and 11 filtering through a 3 μm filter using aheated or unheated stainless steel or glass syringe, and then degassedby applying vacuum at ambient temperature for about 10-20 minutes. In aglove box with a nitrogen gas atmosphere and less than 0.1 percentoxygen gas, about 75-100 μL of the reactive mixture were dosed using anEppendorf pipet at room temperature into the FC. The BC was then placedonto the FC. The molds were equilibrated for a minimum of twelve hoursin the glove box prior to dosing; the mold materials are listed inTables 10-11. Eight trays, each containing eight such mold assemblies,were placed on a mirrored metallic plate and quartz plates were placedon top of the trays to maintain proper fit and alignment. The plate wastransferred into an adjacent glove box maintained at 60-65° C., and thelenses were cured from the top for 12 or 15 minutes as listed in Tables15-17 using TLO3 lights having intensity of 4-5 m W/cm².

The lenses were manually de-molded with most lenses adhering to the FCand released by suspending the 64 lenses in about one liter of aqueousIPA solution for about two or three hours, followed by washing two orthree times with another aqueous IPA solution, two times with DI, andfinally two times with borate buffered packaging solution. The lensrelease process of Example 39 included releasing in 40% IPA overnightthen two IPA washing steps using 40% and 50% IPA prior to the DI and PSwashing steps. The lens release process of Example 45 included two 70%IPA washes lasting 4-5 hours. The concentrations of the aqueous IPAsolutions are listed in Tables 10-11. Each washing step lasted about 30minutes. Lens release is typically performed in jars on a laboratoryroller. The lenses were transferred into vials and subsequentlysterilized by autoclaving at 122° C. for 30 minutes. The physical andmechanical properties of the sterile lenses were measured and listed inTables 18 and 19. NM=not measured.

TABLE 15 Ex 39 Ex Ex Ex Ex Ex Ex Ex Ex Ex Ex Component Ex 38 55 40 41 4243 44 45 46 47 48 49 OH- 45 46.75 30 30 25 20 15 10 10 10 10 10 mPDMS n= 4 OH- 0 0 30 30 35 40 45 50 50 50 50 50 mPDMS n = 15 DMA 12.5 12.5 710 10 10 10 10 10 10 12.5 11.25 HEMA 16.98 16.98 11 11 10.98 10.98 10.9810.98 12.66 12.66 13.48 12.23 pVMA 10 10 10 7 7 7 7 7 0 0 7 7 (507 KDa)pVMA 0 0 0 0 0 0 0 0 7 0 0 0 (549 KDa) AVMA 0 0 0 0 0 0 0 0 0 7 0 0 (700KDa) Tegomer 10 10 10 10 10 10 10 10 10 10 5 7.5 2250 TEGDMA 3.5 1.75 00 0 0 0 0 0 0 0 0 Norbloc 1.75 1.75 1.75 1.75 1.75 1.75 1.75 1.75 0 01.75 1.75 CGI 819 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0.25 0 0 0.25 0.25CGI 1870 0 0 0 0 0 0 0 0 0.34 0.34 0 0 Blue 0.02 0.02 0 0 0.02 0.02 0.020.02 0 0 0.02 0.02 HEMA Cure Time 12 12 12 12 12 12 12 12 15 15 12 12(min) FC 9:1 9:1 NM NM 9:1 9:1 9:1 9:1 PP Z Z Z Material  Z:TT  Z:TT Z:TT  Z:TT  Z:TT  Z:TT BC PP PP NM NM PP PP PP PP 55:45 55:45 55:4555:45 Material  Z:PP  Z:PP  Z:PP  Z:PP % IPA 70 40 NM NM 40 40 40 40 7040 40 40 Release % IPA 70 40 NM NM 40 40 40 40 70 40 40 40 Wash Diluent23 23 23 23 23 23 23 23 23 30 23 23 D3O 100 100 100 100 100 100 100 100100 100 100 100

TABLE 16 Component Ex 50 Ex 51 Ex 52 Ex 53 Ex 54 Ex 55 OH- 15 10 10 1010 10 mPDMS n = 4 OH- 45 50 50 50 50 50 mPDMS n = 15 DMA 10 10 10 10 1212 HEMA 10.98 10.98 12.73 15.73 15.73 15.73 PVP K90 10 10 7 7 5 7Tegomer 7 7 10 7 7 5 2250 Norbloc 1.75 1.75 0 0 0 0 CGI 819 0.25 0.250.25 0.25 0.25 0.25 Blue 0.02 0.02 0.02 0.02 0.02 0.02 HEMA Cure Time 1212 15 15 15 15 (min) FC Material Z Z Z Z Z Z BC Material 55:45 55:4555:45 55:45 55:45 55:45  Z:PP  Z:PP  Z:PP  Z:PP  Z:PP  Z:PP % IPA 40 4040 40 40 40 Release % IPA 40 40 40 40 40 40 Wash Diluent 23 23 23 23 2323 D3O 100 100 100 100 100 100

TABLE 11 Mechanicals Ex % % DCA CT Modulus TS Tough- Elong. # Water Haze(°) D_(k) (μm) (psi) (psi) ness (%) RI 38 29.1 5 NM 107 110 385 182 106101 1.439 39 31.3 7 NM 110 111 297 148 104 120 1.435 40 25.5 10 55 110120 220 144 134 158 1.429 41 25.2 6 94 78 101 180 135 133 166 1.430 4224.5 5 69 96 95 218 115 88 124 1.427 43 23.8 4 92 145 97 182 125 104 1501.427 44 23.1 3 61 125 102 219 150 108 135 1.428 45 24.2 5 70 135 103178 129 116 158 1.425 46 32 18 46 225 124 118 110 154 247 1.415 47 27.712 53 170 122 145 86 66 126 1.420 48 31 17 47 139 101 155 126 140 2011.420 49 31 17 48 262 129 139 123 129 189 1.419 50 NM 8 45 303 113 186111 87 132 1.426 51 NM 9 41 208 113 175 118 132 186 1.425 52 NM 10 37 NM114 147 118 136 191 1.425 53 NM 13 34 NM 119 141 106 139 222 1.420

Example 54

In a glove box with a nitrogen gas atmosphere and less than 0.1 percentoxygen gas, about 20 μL to about 35 μL of the degassed reactive mixturefrom Example 15 was dosed at 60-65° C. into the FC made from a 55:45(w/w) blend of Zeonor:polypropylene. The actual volume was used tocontrol the optical zone. The FC was then irradiated for 2 minutes under420 nm LED lights having an intensity of 4-5 mW/cm² producing apartially cured gel. Thereafter, about 125 μL of the degassed reactivemixture of Table was dosed into the FC on top of the aforementionedpartially cured gel. A BC made from Zeonor was placed on the front curvemold. A quartz plate was placed on top of a tray of eight such moldassemblies to maintain proper fitting. The molds were equilibrated for aminimum of twelve hours in the glove box prior to dosing. The lenseswere cured from the bottom for 18 minutes using 420 nm LED lights havingintensity of 4-5 mW/cm².

The lenses were solvent released from the molds by the following methodwhich prevented any damage to the lenses because of the differences inthe two formulations: (1) suspended in 20% IPA overnight, 20% IPA forone hour, 30% IPA for 2-4 hours, 40% IPA overnight, 30% IPA for 2-4hours, 20% IPA overnight, and finally DI water overnight. The lenseswere sterilized by autoclaving at 122° C. for 30 minutes.

The properties for the hydrogel used in the peripheral and central zonesare listed in Table 12, below. The resulting contact lens was evaluatedfor astigmatic masking using an in vitro test method in which thecontact lens is fitted on an eye model and optical coherence tomography(OCT) was used to generate an image of the contact lens on the modeleye. In FIG. 1, an OCT image demonstrating that the contact lensprepared in Example 49 was able to vault over the corneal region of theeye model thereby providing a gap filled with artificial tear fluid thatfrom an optics point of view masks any astigmatism on the cornea.

TABLE 11 peripheral reactive Component mixture OH-mPDMS n = 4 10OH-mPDMS n = 15 50 DMA 10 HEMA 10.98 pVMA (507 KDa) 7 Tegomer 2250 10Norbloc 1.75 CGI 819 0.25 Blue HEMA 0.02 Diluent 23 D3O 100

TABLE 12 Mechanical Properties Sessile % % Mod Elong TS Tough- zone dropwater haze (psi) (%) (psi) ness Central 37 22 26 41181 11 2148 106  (8) (0)  (2)  (2385)  (1)  (149)  (26) Periph. 65 24 5 178 158 129 116  (6) (0) (0)  (12)  (42)  (29)  (53) Mechanical Properties Sessile % % ModElong TS Tough- zone drop water haze (psi) (%) (psi) ness Central 37 2226 41181 11 2148 106  (8)  (0)  (2)  (2385)  (1)  (149)  (26) Periph. 6524 5 178 158 129 116  (6)  (0) (0)  (12)  (42)  (29)  (53)

Although shown and described is what is believed to be the mostpractical and preferred embodiments, it is apparent that departures fromspecific designs and methods described and shown will suggest themselvesto those skilled in the art and may be used without departing from thespirit and scope of the invention. The present invention is notrestricted to the particular constructions described and illustrated,but should be constructed to cohere with all modifications that may fallwithin the scope of the appended claims.

What is claimed is:
 1. An ophthalmic device comprising: a contact lenshaving a central optic zone and a peripheral zone surrounding thecentral optic zone, the peripheral zone being formed from a secondmaterial having a second Young's modulus; and a first materialincorporated into the central optic zone of the contact lens, the firstmaterial having a first Young's modulus of at least about 1000 psi and awater content of at least about 10%, formed from a first reactivemixture comprising at least one N-alkyl methacrylamide and at least onesilicone-containing component.
 2. The ophthalmic device of claim 1wherein said first material further comprising a water content of about20 to about 40%.
 3. The ophthalmic device of claim 1 or 2 wherein saidfirst reactive mixture further comprises at least one photoinitiator. 4.The ophthalmic device of claim 1 wherein said silicone hydrogel is curedvia exposure to light, or visible light.
 5. The ophthalmic device of anyof the foregoing claims wherein said silicone containing componentcomprises at least one silicone chain having 3-30 siloxane repeatingunits.
 6. The ophthalmic device of claim 5 wherein said at least onesilicone chain is a polydialkyl siloxane chain.
 7. The ophthalmic deviceof claim 5 wherein said at least one silicone chain is a polydimethylsiloxane chain.
 8. The silicone hydrogel of claim 5 wherein said atleast one silicone chain is a polydiaryl siloxane chain.
 9. Theophthalmic device of any of the foregoing claims wherein said firstreactive mixture comprises about 20 to about 60 wt % of said siliconecontaining component, based upon all reactive components.
 10. Theophthalmic device of any of the foregoing claims wherein said firstreactive mixture comprises about 5 wt % to about 50 wt % of at least oneN-alkyl methacrylamide, based upon all reactive components.
 11. Theophthalmic device of any of the foregoing claims wherein the secondmaterial is formed from a reaction mixture containing asilicone-containing component, said silicone-containing component isselected from compounds of Formulae IIIa through IVc, and combinationsthereof:

wherein R¹ is a hydrogen atom or methyl; Z is selected from O, N, S orNR₁CH₂CH₂O; when Z═O or S, R² is not required; wherein j is a wholenumber between 1 and 20; wherein R¹⁹ is a substituted or unsubstitutedC₁₋₆, C₁₋₄ or C₂₋₄ alkylene segment (CH₂)_(r) each methylene group mayoptionally be independently substituted with ethers, amines, carbonyls,carboxylates, carbamates and combinations thereof; or an oxyalkylenesegment (OCH₂)_(k) and k is a whole number from one to three, or whereinR¹⁹ may be a mixture of alkylene and oxyalkylene segments and the sum ofr and k is between 1 and 9; wherein each R³ and R⁴ are independently alinear, branched, or cyclic alkyl group containing between one and sixcarbon atoms, a linear, branched, or cyclic alkoxy group containingbetween one and six carbon atoms, a linear or branchedpolyethyleneoxyalkyl group, a phenyl group, a benzyl group, asubstituted or un-substituted aryl group, a fluoroalkyl group, apartially fluorinated alkyl group, a perfluoroalkyl group, a fluorineatom, or combinations thereof; wherein R⁵ is a substituted orun-substituted linear or branched alkyl group having 1 to eight carbonatoms, or 1 to 4 carbon atoms, or methyl or butyl; or an aryl group, anyof which may be substituted with one or more fluorine atoms.
 12. Theophthalmic device of any of the foregoing claims wherein said at leastone N-alkyl methacrylamide has the formula

wherein R′ is selected from linear, branched, or cyclic alkyl groupscontaining one to eight carbon atoms, benzyl or phenyl, any of which maybe un-substituted or substituted with additional functional groups suchas hydroxyl, amino, and combinations thereof.
 13. The ophthalmic deviceof claim 12 wherein said N-alkyl methacrylamide is N-methylmethacrylamide.
 14. The ophthalmic device of any of the foregoing claimswherein said first material has a modulus of about 1000 psi to about200,000 psi, said first reactive mixture comprises about 5 to about 15wt % at least one crosslinking component.
 15. The silicone hydrogel ofclaim 14 wherein said modulus is about 1000 to about 100,000 psi, orabout 5000 to about 100,000 psi.
 16. The ophthalmic device of claim 14wherein said first reactive mixture comprises about 20 to about 80 wt %or 30-80 wt % of said silicone containing component, based upon allreactive components.
 17. The ophthalmic device of claim 14 wherein saidfirst reactive mixture comprises about 5 wt % to about 50 wt % of atleast one N-alkyl methacrylamide, based upon all reactive components.18. The ophthalmic device of claim 14 wherein said first reactivemixture further comprises about 5 wt % to about 40 wt % of at least onehydroxyl functional silicone containing component.
 19. The ophthalmicdevice of claim 18 wherein said hydroxyl functional silicone containingcomponent is a hydroxyl functional polysiloxane selected from the groupconsisting of polydialkyl siloxanes and polydiaryl siloxanes.
 20. Theophthalmic device of claim 19 wherein said first reactive mixturecomprise about 10 to about 40 wt % hydroxyl functional polysiloxane. 21.The ophthalmic device of claim 19 or 20 wherein said hydroxyl functionalpolysiloxane comprises at least one polydimethyl siloxane.
 22. Theophthalmic device of claim 19 or 20 wherein said hydroxyl functionalsilicone containing component is selected from the group consisting ofmonofunctional hydroxyl substituted poly(disubstituted siloxane)s ofFormula XXI:

wherein Z is selected from O, N, S or NR¹CH₂CH₂O, when Z is O or S R² isnot present; R¹ is independently H or methyl; R², R³ and R⁴ areindependently a linear, branched, or cyclic alkyl group containing oneto eight carbon atoms, any of which may be further substituted with atleast one hydroxy group, and which may be optionally substituted withamide, ether, and combinations thereof; R³ and R⁴ may be independentlyselected from methyl, ethyl or phenyl, or may be methyl; n is the numberof siloxane units and is from 4 to 8 for the first monofunctionalhydroxyl substituted poly(disubstituted siloxane) monomer, and R⁵ isselected from straight or branched C₁ to C₈ alkyl groups, which may beoptionally substituted with one or more hydroxyl, amide, ether, andcombinations thereof; R⁵ may be straight or branched C₄ alkyl, either ofwhich may optionally be substituted with hydroxyl, or may be methyl. 23.The ophthalmic device of claim 19 or 20 wherein said hydroxyl functionalsilicone-containing component comprisesmono-(2-hydroxy-3-methacryloxypropyl)-propyl ether terminatedmono-n-butyl terminated polydimethylsiloxanes (OH-mPDMS) as shown inFormula XXIIa wherein n is between 4 and 30; and polydimethylsiloxaneshaving the chemical structures as shown in Formulae XXIIb throughXXIIId, where n is between 4 and 30; n¹ n², and n³ are independentlybetween 4 to 100; R⁵ is selected from straight or branched C₁ to C₈alkyl groups, which may be optionally substituted with one or morehydroxyl, amide, ether, polyhydroxyl groups selected from straight orbranched C₁ to C₈ groups having a formula of C_(f)H_(g)(OH)_(h) whereinf=1-8 and g+h=2f+1 and cyclic C₁ to C₈ groups having a formula ofC_(f)H_(g)(OH)_(h) wherein f=1-8 and g+h=2f−1, and combinations thereof;or R⁵ may be selected from methyl, butyl or hydroxyl substituted C₂-C₅alkyl, and polycarbosiloxanes of Formula XXIV where a and b are between4-100 and c is 4-8 and R¹ and R⁵ are as defined above:


24. The ophthalmic device of any of the foregoing claims wherein saidfirst reactive mixture further comprises at least onesilicone-containing crosslinker.
 25. The ophthalmic device of any of theforegoing claims wherein said first reactive mixture comprises about 4to about 15 wt % said silicone-containing crosslinker.
 26. Theophthalmic device of claim 24 wherein said silicone-containingcrosslinker has the structure of Formula XXVI-XXXVI:

wherein n is between 1 and 200, 50 and 150, 50 and 100, or 10 and 50.27. The ophthalmic device of any of claims 15-26 wherein said at leastone N-alkyl methacrylamide has the formula

wherein R₁ is selected from linear, branched, or cyclic alkyl groupscontaining one to eight carbon atoms, benzyl or phenyl, any of which maybe un-substituted or substituted with additional functional groups suchas hydroxyl, amino.
 28. The ophthalmic device of claim 27 wherein saidN-alkyl methacrylamide is N-methyl methacrylamide.
 29. The ophthalmicdevice of any of the foregoing claims wherein said first reactivemixture comprises about 20 to about 80 wt % of said silicone containingcomponent, based upon all reactive components.
 30. The ophthalmic deviceof any of the foregoing claims wherein said first reactive mixturecomprises about 5 wt % to about 50 wt % of said at least one N-alkylmethacrylamide, based upon all reactive components.
 31. The ophthalmicdevice of any of the foregoing claims, wherein the ophthalmic devicecomprises a toric contact lens.
 32. The ophthalmic device according toany of the foregoing claims, wherein the second material comprisesYoung's modulus less than about 200 psi or 150 psi.
 33. The contact lensof any of the foregoing claims wherein said central zone is about 9 mmor less in diameter.
 34. The contact lens of any of the foregoing claimswherein said central zone has a diameter of between about 4 and about 7mm.
 35. A contact lens comprising: an optic zone being formed from afirst material having a first Young's modulus between about 1,000 psiand about 200,000 psi, said first material formed from a reactivemixture comprising at least one N-alkyl methacrylamide and at least onesilicone-containing component; and a peripheral zone formed from amaterial having a second Young's modulus less than about 200 psi.
 36. Acontact lens comprising: an optic zone having a first stiffness, saidoptic zone being formed from a first material having a first Young'smodulus between about 1,000 psi and about 200,000 psi, said firstmaterial formed from a reactive mixture comprising at least one N-alkylmethacrylamide and at least one silicone-containing component; and aperipheral zone having a second stiffness formed from a material havinga second Young's modulus less than about 200 psi, the first stiffnessbeing greater than the second stiffness.